Adding upstream version 1:9.11.5.P4+dfsg.upstream/1%9.11.5.P4+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3501 insertions, 0 deletions

diff --git a/bin/named/update.c b/bin/named/update.c
new file mode 100644
index 0000000..973dda5
--- /dev/null
+++ b/bin/named/update.c
@@ -0,0 +1,3501 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#include <config.h>
+
+#include <inttypes.h>
+#include <stdbool.h>
+
+#include <isc/netaddr.h>
+#include <isc/print.h>
+#include <isc/serial.h>
+#include <isc/stats.h>
+#include <isc/string.h>
+#include <isc/taskpool.h>
+#include <isc/util.h>
+
+#include <dns/db.h>
+#include <dns/dbiterator.h>
+#include <dns/diff.h>
+#include <dns/dnssec.h>
+#include <dns/events.h>
+#include <dns/fixedname.h>
+#include <dns/journal.h>
+#include <dns/keyvalues.h>
+#include <dns/message.h>
+#include <dns/nsec.h>
+#include <dns/nsec3.h>
+#include <dns/private.h>
+#include <dns/rdataclass.h>
+#include <dns/rdataset.h>
+#include <dns/rdatasetiter.h>
+#include <dns/rdatastruct.h>
+#include <dns/rdatatype.h>
+#include <dns/soa.h>
+#include <dns/ssu.h>
+#include <dns/tsig.h>
+#include <dns/update.h>
+#include <dns/view.h>
+#include <dns/zone.h>
+#include <dns/zt.h>
+
+#include <named/client.h>
+#include <named/log.h>
+#include <named/server.h>
+#include <named/update.h>
+
+/*! \file
+ * \brief
+ * This module implements dynamic update as in RFC2136.
+ */
+
+/*
+ *  XXX TODO:
+ * - document strict minimality
+ */
+
+/**************************************************************************/
+
+/*%
+ * Log level for tracing dynamic update protocol requests.
+ */
+#define LOGLEVEL_PROTOCOL	ISC_LOG_INFO
+
+/*%
+ * Log level for low-level debug tracing.
+ */
+#define LOGLEVEL_DEBUG		ISC_LOG_DEBUG(8)
+
+/*%
+ * Check an operation for failure.  These macros all assume that
+ * the function using them has a 'result' variable and a 'failure'
+ * label.
+ */
+#define CHECK(op) \
+	do { result = (op); \
+		if (result != ISC_R_SUCCESS) goto failure; \
+	} while (0)
+
+/*%
+ * Fail unconditionally with result 'code', which must not
+ * be ISC_R_SUCCESS.  The reason for failure presumably has
+ * been logged already.
+ *
+ * The test against ISC_R_SUCCESS is there to keep the Solaris compiler
+ * from complaining about "end-of-loop code not reached".
+ */
+
+#define FAIL(code) \
+	do {							\
+		result = (code);				\
+		if (result != ISC_R_SUCCESS) goto failure;	\
+	} while (0)
+
+/*%
+ * Fail unconditionally and log as a client error.
+ * The test against ISC_R_SUCCESS is there to keep the Solaris compiler
+ * from complaining about "end-of-loop code not reached".
+ */
+#define FAILC(code, msg) \
+	do {							\
+		const char *_what = "failed";			\
+		result = (code);				\
+		switch (result) {				\
+		case DNS_R_NXDOMAIN:				\
+		case DNS_R_YXDOMAIN:				\
+		case DNS_R_YXRRSET:				\
+		case DNS_R_NXRRSET:				\
+			_what = "unsuccessful";			\
+		}						\
+		update_log(client, zone, LOGLEVEL_PROTOCOL,	\
+			   "update %s: %s (%s)", _what,		\
+			   msg, isc_result_totext(result));	\
+		if (result != ISC_R_SUCCESS) goto failure;	\
+	} while (0)
+#define PREREQFAILC(code, msg) \
+	do {							\
+		inc_stats(zone, dns_nsstatscounter_updatebadprereq); \
+		FAILC(code, msg);				\
+	} while (0)
+
+#define FAILN(code, name, msg) \
+	do {								\
+		const char *_what = "failed";				\
+		result = (code);					\
+		switch (result) {					\
+		case DNS_R_NXDOMAIN:					\
+		case DNS_R_YXDOMAIN:					\
+		case DNS_R_YXRRSET:					\
+		case DNS_R_NXRRSET:					\
+			_what = "unsuccessful";				\
+		}							\
+		if (isc_log_wouldlog(ns_g_lctx, LOGLEVEL_PROTOCOL)) {	\
+			char _nbuf[DNS_NAME_FORMATSIZE];		\
+			dns_name_format(name, _nbuf, sizeof(_nbuf));	\
+			update_log(client, zone, LOGLEVEL_PROTOCOL,	\
+				   "update %s: %s: %s (%s)", _what, _nbuf, \
+				   msg, isc_result_totext(result));	\
+		}							\
+		if (result != ISC_R_SUCCESS) goto failure;		\
+	} while (0)
+#define PREREQFAILN(code, name, msg) \
+	do {								\
+		inc_stats(zone, dns_nsstatscounter_updatebadprereq); \
+		FAILN(code, name, msg);					\
+	} while (0)
+
+#define FAILNT(code, name, type, msg) \
+	do {								\
+		const char *_what = "failed";				\
+		result = (code);					\
+		switch (result) {					\
+		case DNS_R_NXDOMAIN:					\
+		case DNS_R_YXDOMAIN:					\
+		case DNS_R_YXRRSET:					\
+		case DNS_R_NXRRSET:					\
+			_what = "unsuccessful";				\
+		}							\
+		if (isc_log_wouldlog(ns_g_lctx, LOGLEVEL_PROTOCOL)) {	\
+			char _nbuf[DNS_NAME_FORMATSIZE];		\
+			char _tbuf[DNS_RDATATYPE_FORMATSIZE];		\
+			dns_name_format(name, _nbuf, sizeof(_nbuf));	\
+			dns_rdatatype_format(type, _tbuf, sizeof(_tbuf)); \
+			update_log(client, zone, LOGLEVEL_PROTOCOL,	\
+				   "update %s: %s/%s: %s (%s)",		\
+				   _what, _nbuf, _tbuf, msg,		\
+				   isc_result_totext(result));		\
+		}							\
+		if (result != ISC_R_SUCCESS) goto failure;		\
+	} while (0)
+#define PREREQFAILNT(code, name, type, msg)				\
+	do {								\
+		inc_stats(zone, dns_nsstatscounter_updatebadprereq); \
+		FAILNT(code, name, type, msg);				\
+	} while (0)
+
+/*%
+ * Fail unconditionally and log as a server error.
+ * The test against ISC_R_SUCCESS is there to keep the Solaris compiler
+ * from complaining about "end-of-loop code not reached".
+ */
+#define FAILS(code, msg) \
+	do {							\
+		result = (code);				\
+		update_log(client, zone, LOGLEVEL_PROTOCOL,	\
+			   "error: %s: %s",			\
+			   msg, isc_result_totext(result));	\
+		if (result != ISC_R_SUCCESS) goto failure;	\
+	} while (0)
+
+/*
+ * Return TRUE if NS_CLIENTATTR_TCP is set in the attributes other FALSE.
+ */
+#define TCPCLIENT(client) (((client)->attributes & NS_CLIENTATTR_TCP) != 0)
+
+/**************************************************************************/
+
+typedef struct rr rr_t;
+
+struct rr {
+	/* dns_name_t name; */
+	uint32_t		ttl;
+	dns_rdata_t		rdata;
+};
+
+typedef struct update_event update_event_t;
+
+struct update_event {
+	ISC_EVENT_COMMON(update_event_t);
+	dns_zone_t		*zone;
+	isc_result_t		result;
+	dns_message_t		*answer;
+};
+
+/*%
+ * Prepare an RR for the addition of the new RR 'ctx->update_rr',
+ * with TTL 'ctx->update_rr_ttl', to its rdataset, by deleting
+ * the RRs if it is replaced by the new RR or has a conflicting TTL.
+ * The necessary changes are appended to ctx->del_diff and ctx->add_diff;
+ * we need to do all deletions before any additions so that we don't run
+ * into transient states with conflicting TTLs.
+ */
+
+typedef struct {
+	dns_db_t *db;
+	dns_dbversion_t *ver;
+	dns_diff_t *diff;
+	dns_name_t *name;
+	dns_name_t *oldname;
+	dns_rdata_t *update_rr;
+	dns_ttl_t update_rr_ttl;
+	bool ignore_add;
+	dns_diff_t del_diff;
+	dns_diff_t add_diff;
+} add_rr_prepare_ctx_t;
+
+/**************************************************************************/
+/*
+ * Forward declarations.
+ */
+
+static void update_action(isc_task_t *task, isc_event_t *event);
+static void updatedone_action(isc_task_t *task, isc_event_t *event);
+static isc_result_t send_forward_event(ns_client_t *client, dns_zone_t *zone);
+static void forward_done(isc_task_t *task, isc_event_t *event);
+static isc_result_t add_rr_prepare_action(void *data, rr_t *rr);
+
+/**************************************************************************/
+
+static void
+update_log(ns_client_t *client, dns_zone_t *zone,
+	   int level, const char *fmt, ...) ISC_FORMAT_PRINTF(4, 5);
+
+static void
+update_log(ns_client_t *client, dns_zone_t *zone,
+	   int level, const char *fmt, ...)
+{
+	va_list ap;
+	char message[4096];
+	char namebuf[DNS_NAME_FORMATSIZE];
+	char classbuf[DNS_RDATACLASS_FORMATSIZE];
+
+	if (client == NULL || zone == NULL)
+		return;
+
+	if (isc_log_wouldlog(ns_g_lctx, level) == false)
+		return;
+
+	dns_name_format(dns_zone_getorigin(zone), namebuf,
+			sizeof(namebuf));
+	dns_rdataclass_format(dns_zone_getclass(zone), classbuf,
+			      sizeof(classbuf));
+
+	va_start(ap, fmt);
+	vsnprintf(message, sizeof(message), fmt, ap);
+	va_end(ap);
+
+	ns_client_log(client, NS_LOGCATEGORY_UPDATE, NS_LOGMODULE_UPDATE,
+		      level, "updating zone '%s/%s': %s",
+		      namebuf, classbuf, message);
+}
+
+static void
+update_log_cb(void *arg, dns_zone_t *zone, int level, const char *message) {
+	update_log(arg, zone, level, "%s", message);
+}
+
+/*%
+ * Increment updated-related statistics counters.
+ */
+static inline void
+inc_stats(dns_zone_t *zone, isc_statscounter_t counter) {
+	isc_stats_increment(ns_g_server->nsstats, counter);
+
+	if (zone != NULL) {
+		isc_stats_t *zonestats = dns_zone_getrequeststats(zone);
+		if (zonestats != NULL)
+			isc_stats_increment(zonestats, counter);
+	}
+}
+
+/*%
+ * Check if we could have queried for the contents of this zone or
+ * if the zone is potentially updateable.
+ * If the zone can potentially be updated and the check failed then
+ * log a error otherwise we log a informational message.
+ */
+static isc_result_t
+checkqueryacl(ns_client_t *client, dns_acl_t *queryacl, dns_name_t *zonename,
+	      dns_acl_t *updateacl, dns_ssutable_t *ssutable)
+{
+	char namebuf[DNS_NAME_FORMATSIZE];
+	char classbuf[DNS_RDATACLASS_FORMATSIZE];
+	int level;
+	isc_result_t result;
+
+	result = ns_client_checkaclsilent(client, NULL, queryacl, true);
+	if (result != ISC_R_SUCCESS) {
+		dns_name_format(zonename, namebuf, sizeof(namebuf));
+		dns_rdataclass_format(client->view->rdclass, classbuf,
+				      sizeof(classbuf));
+
+		level = (updateacl == NULL && ssutable == NULL) ?
+				ISC_LOG_INFO : ISC_LOG_ERROR;
+
+		ns_client_log(client, NS_LOGCATEGORY_UPDATE_SECURITY,
+			      NS_LOGMODULE_UPDATE, level,
+			      "update '%s/%s' denied due to allow-query",
+			      namebuf, classbuf);
+	} else if (updateacl == NULL && ssutable == NULL) {
+		dns_name_format(zonename, namebuf, sizeof(namebuf));
+		dns_rdataclass_format(client->view->rdclass, classbuf,
+				      sizeof(classbuf));
+
+		result = DNS_R_REFUSED;
+		ns_client_log(client, NS_LOGCATEGORY_UPDATE_SECURITY,
+			      NS_LOGMODULE_UPDATE, ISC_LOG_INFO,
+			      "update '%s/%s' denied", namebuf, classbuf);
+	}
+	return (result);
+}
+
+/*%
+ * Override the default acl logging when checking whether a client
+ * can update the zone or whether we can forward the request to the
+ * master based on IP address.
+ *
+ * 'message' contains the type of operation that is being attempted.
+ * 'slave' indicates if this is a slave zone.  If 'acl' is NULL then
+ * log at debug=3.
+ * If the zone has no access controls configured ('acl' == NULL &&
+ * 'has_ssutable == ISC_FALS) log the attempt at info, otherwise
+ * at error.
+ *
+ * If the request was signed log that we received it.
+ */
+static isc_result_t
+checkupdateacl(ns_client_t *client, dns_acl_t *acl, const char *message,
+	       dns_name_t *zonename, bool slave,
+	       bool has_ssutable)
+{
+	char namebuf[DNS_NAME_FORMATSIZE];
+	char classbuf[DNS_RDATACLASS_FORMATSIZE];
+	int level = ISC_LOG_ERROR;
+	const char *msg = "denied";
+	isc_result_t result;
+
+	if (slave && acl == NULL) {
+		result = DNS_R_NOTIMP;
+		level = ISC_LOG_DEBUG(3);
+		msg = "disabled";
+	} else {
+		result = ns_client_checkaclsilent(client, NULL, acl, false);
+		if (result == ISC_R_SUCCESS) {
+			level = ISC_LOG_DEBUG(3);
+			msg = "approved";
+		} else if (acl == NULL && !has_ssutable) {
+			level = ISC_LOG_INFO;
+		}
+	}
+
+	if (client->signer != NULL) {
+		dns_name_format(client->signer, namebuf, sizeof(namebuf));
+		ns_client_log(client, NS_LOGCATEGORY_UPDATE_SECURITY,
+			      NS_LOGMODULE_UPDATE, ISC_LOG_INFO,
+			      "signer \"%s\" %s", namebuf, msg);
+	}
+
+	dns_name_format(zonename, namebuf, sizeof(namebuf));
+	dns_rdataclass_format(client->view->rdclass, classbuf,
+			      sizeof(classbuf));
+
+	ns_client_log(client, NS_LOGCATEGORY_UPDATE_SECURITY,
+		      NS_LOGMODULE_UPDATE, level, "%s '%s/%s' %s",
+		      message, namebuf, classbuf, msg);
+	return (result);
+}
+
+/*%
+ * Update a single RR in version 'ver' of 'db' and log the
+ * update in 'diff'.
+ *
+ * Ensures:
+ * \li	'*tuple' == NULL.  Either the tuple is freed, or its
+ *	ownership has been transferred to the diff.
+ */
+static isc_result_t
+do_one_tuple(dns_difftuple_t **tuple, dns_db_t *db, dns_dbversion_t *ver,
+	     dns_diff_t *diff)
+{
+	dns_diff_t temp_diff;
+	isc_result_t result;
+
+	/*
+	 * Create a singleton diff.
+	 */
+	dns_diff_init(diff->mctx, &temp_diff);
+	ISC_LIST_APPEND(temp_diff.tuples, *tuple, link);
+
+	/*
+	 * Apply it to the database.
+	 */
+	result = dns_diff_apply(&temp_diff, db, ver);
+	ISC_LIST_UNLINK(temp_diff.tuples, *tuple, link);
+	if (result != ISC_R_SUCCESS) {
+		dns_difftuple_free(tuple);
+		return (result);
+	}
+
+	/*
+	 * Merge it into the current pending journal entry.
+	 */
+	dns_diff_appendminimal(diff, tuple);
+
+	/*
+	 * Do not clear temp_diff.
+	 */
+	return (ISC_R_SUCCESS);
+}
+
+/*%
+ * Perform the updates in 'updates' in version 'ver' of 'db' and log the
+ * update in 'diff'.
+ *
+ * Ensures:
+ * \li	'updates' is empty.
+ */
+static isc_result_t
+do_diff(dns_diff_t *updates, dns_db_t *db, dns_dbversion_t *ver,
+	dns_diff_t *diff)
+{
+	isc_result_t result;
+	while (! ISC_LIST_EMPTY(updates->tuples)) {
+		dns_difftuple_t *t = ISC_LIST_HEAD(updates->tuples);
+		ISC_LIST_UNLINK(updates->tuples, t, link);
+		CHECK(do_one_tuple(&t, db, ver, diff));
+	}
+	return (ISC_R_SUCCESS);
+
+ failure:
+	dns_diff_clear(diff);
+	return (result);
+}
+
+static isc_result_t
+update_one_rr(dns_db_t *db, dns_dbversion_t *ver, dns_diff_t *diff,
+	      dns_diffop_t op, dns_name_t *name, dns_ttl_t ttl,
+	      dns_rdata_t *rdata)
+{
+	dns_difftuple_t *tuple = NULL;
+	isc_result_t result;
+	result = dns_difftuple_create(diff->mctx, op,
+				      name, ttl, rdata, &tuple);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+	return (do_one_tuple(&tuple, db, ver, diff));
+}
+
+/**************************************************************************/
+/*
+ * Callback-style iteration over rdatasets and rdatas.
+ *
+ * foreach_rrset() can be used to iterate over the RRsets
+ * of a name and call a callback function with each
+ * one.  Similarly, foreach_rr() can be used to iterate
+ * over the individual RRs at name, optionally restricted
+ * to RRs of a given type.
+ *
+ * The callback functions are called "actions" and take
+ * two arguments: a void pointer for passing arbitrary
+ * context information, and a pointer to the current RRset
+ * or RR.  By convention, their names end in "_action".
+ */
+
+/*
+ * XXXRTH  We might want to make this public somewhere in libdns.
+ */
+
+/*%
+ * Function type for foreach_rrset() iterator actions.
+ */
+typedef isc_result_t rrset_func(void *data, dns_rdataset_t *rrset);
+
+/*%
+ * Function type for foreach_rr() iterator actions.
+ */
+typedef isc_result_t rr_func(void *data, rr_t *rr);
+
+/*%
+ * Internal context struct for foreach_node_rr().
+ */
+typedef struct {
+	rr_func *	rr_action;
+	void *		rr_action_data;
+} foreach_node_rr_ctx_t;
+
+/*%
+ * Internal helper function for foreach_node_rr().
+ */
+static isc_result_t
+foreach_node_rr_action(void *data, dns_rdataset_t *rdataset) {
+	isc_result_t result;
+	foreach_node_rr_ctx_t *ctx = data;
+	for (result = dns_rdataset_first(rdataset);
+	     result == ISC_R_SUCCESS;
+	     result = dns_rdataset_next(rdataset))
+	{
+		rr_t rr = { 0, DNS_RDATA_INIT };
+
+		dns_rdataset_current(rdataset, &rr.rdata);
+		rr.ttl = rdataset->ttl;
+		result = (*ctx->rr_action)(ctx->rr_action_data, &rr);
+		if (result != ISC_R_SUCCESS)
+			return (result);
+	}
+	if (result != ISC_R_NOMORE)
+		return (result);
+	return (ISC_R_SUCCESS);
+}
+
+/*%
+ * For each rdataset of 'name' in 'ver' of 'db', call 'action'
+ * with the rdataset and 'action_data' as arguments.  If the name
+ * does not exist, do nothing.
+ *
+ * If 'action' returns an error, abort iteration and return the error.
+ */
+static isc_result_t
+foreach_rrset(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
+	      rrset_func *action, void *action_data)
+{
+	isc_result_t result;
+	dns_dbnode_t *node;
+	dns_rdatasetiter_t *iter;
+	dns_clientinfomethods_t cm;
+	dns_clientinfo_t ci;
+	dns_dbversion_t *oldver = NULL;
+
+	dns_clientinfomethods_init(&cm, ns_client_sourceip);
+
+	/*
+	 * Only set the clientinfo 'versionp' if the new version is
+	 * different from the current version
+	 */
+	dns_db_currentversion(db, &oldver);
+	dns_clientinfo_init(&ci, NULL, (ver != oldver) ? ver : NULL);
+	dns_db_closeversion(db, &oldver, false);
+
+	node = NULL;
+	result = dns_db_findnodeext(db, name, false, &cm, &ci, &node);
+	if (result == ISC_R_NOTFOUND)
+		return (ISC_R_SUCCESS);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	iter = NULL;
+	result = dns_db_allrdatasets(db, node, ver,
+				     (isc_stdtime_t) 0, &iter);
+	if (result != ISC_R_SUCCESS)
+		goto cleanup_node;
+
+	for (result = dns_rdatasetiter_first(iter);
+	     result == ISC_R_SUCCESS;
+	     result = dns_rdatasetiter_next(iter))
+	{
+		dns_rdataset_t rdataset;
+
+		dns_rdataset_init(&rdataset);
+		dns_rdatasetiter_current(iter, &rdataset);
+
+		result = (*action)(action_data, &rdataset);
+
+		dns_rdataset_disassociate(&rdataset);
+		if (result != ISC_R_SUCCESS)
+			goto cleanup_iterator;
+	}
+	if (result == ISC_R_NOMORE)
+		result = ISC_R_SUCCESS;
+
+ cleanup_iterator:
+	dns_rdatasetiter_destroy(&iter);
+
+ cleanup_node:
+	dns_db_detachnode(db, &node);
+
+	return (result);
+}
+
+/*%
+ * For each RR of 'name' in 'ver' of 'db', call 'action'
+ * with the RR and 'action_data' as arguments.  If the name
+ * does not exist, do nothing.
+ *
+ * If 'action' returns an error, abort iteration
+ * and return the error.
+ */
+static isc_result_t
+foreach_node_rr(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
+		rr_func *rr_action, void *rr_action_data)
+{
+	foreach_node_rr_ctx_t ctx;
+	ctx.rr_action = rr_action;
+	ctx.rr_action_data = rr_action_data;
+	return (foreach_rrset(db, ver, name,
+			      foreach_node_rr_action, &ctx));
+}
+
+
+/*%
+ * For each of the RRs specified by 'db', 'ver', 'name', 'type',
+ * (which can be dns_rdatatype_any to match any type), and 'covers', call
+ * 'action' with the RR and 'action_data' as arguments. If the name
+ * does not exist, or if no RRset of the given type exists at the name,
+ * do nothing.
+ *
+ * If 'action' returns an error, abort iteration and return the error.
+ */
+static isc_result_t
+foreach_rr(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
+	   dns_rdatatype_t type, dns_rdatatype_t covers, rr_func *rr_action,
+	   void *rr_action_data)
+{
+
+	isc_result_t result;
+	dns_dbnode_t *node;
+	dns_rdataset_t rdataset;
+	dns_clientinfomethods_t cm;
+	dns_clientinfo_t ci;
+	dns_dbversion_t *oldver = NULL;
+	dns_fixedname_t fixed;
+
+	dns_clientinfomethods_init(&cm, ns_client_sourceip);
+
+	/*
+	 * Only set the clientinfo 'versionp' if the new version is
+	 * different from the current version
+	 */
+	dns_db_currentversion(db, &oldver);
+	dns_clientinfo_init(&ci, NULL, (ver != oldver) ? ver : NULL);
+	dns_db_closeversion(db, &oldver, false);
+
+	if (type == dns_rdatatype_any)
+		return (foreach_node_rr(db, ver, name,
+					rr_action, rr_action_data));
+
+	node = NULL;
+	if (type == dns_rdatatype_nsec3 ||
+	    (type == dns_rdatatype_rrsig && covers == dns_rdatatype_nsec3))
+		result = dns_db_findnsec3node(db, name, false, &node);
+	else
+		result = dns_db_findnodeext(db, name, false,
+					    &cm, &ci, &node);
+	if (result == ISC_R_NOTFOUND)
+		return (ISC_R_SUCCESS);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	dns_rdataset_init(&rdataset);
+	result = dns_db_findrdataset(db, node, ver, type, covers,
+				     (isc_stdtime_t) 0, &rdataset, NULL);
+	if (result == ISC_R_NOTFOUND) {
+		result = ISC_R_SUCCESS;
+		goto cleanup_node;
+	}
+	if (result != ISC_R_SUCCESS)
+		goto cleanup_node;
+
+	if (rr_action == add_rr_prepare_action) {
+		add_rr_prepare_ctx_t *ctx = rr_action_data;
+
+		ctx->oldname = dns_fixedname_initname(&fixed);
+		dns_name_copy(name, ctx->oldname, NULL);
+		dns_rdataset_getownercase(&rdataset, ctx->oldname);
+	}
+
+	for (result = dns_rdataset_first(&rdataset);
+	     result == ISC_R_SUCCESS;
+	     result = dns_rdataset_next(&rdataset))
+	{
+		rr_t rr = { 0, DNS_RDATA_INIT };
+		dns_rdataset_current(&rdataset, &rr.rdata);
+		rr.ttl = rdataset.ttl;
+		result = (*rr_action)(rr_action_data, &rr);
+		if (result != ISC_R_SUCCESS)
+			goto cleanup_rdataset;
+	}
+	if (result != ISC_R_NOMORE)
+		goto cleanup_rdataset;
+	result = ISC_R_SUCCESS;
+
+ cleanup_rdataset:
+	dns_rdataset_disassociate(&rdataset);
+ cleanup_node:
+	dns_db_detachnode(db, &node);
+
+	return (result);
+}
+
+/**************************************************************************/
+/*
+ * Various tests on the database contents (for prerequisites, etc).
+ */
+
+/*%
+ * Function type for predicate functions that compare a database RR 'db_rr'
+ * against an update RR 'update_rr'.
+ */
+typedef bool rr_predicate(dns_rdata_t *update_rr, dns_rdata_t *db_rr);
+
+/*%
+ * Helper function for rrset_exists().
+ */
+static isc_result_t
+rrset_exists_action(void *data, rr_t *rr) {
+	UNUSED(data);
+	UNUSED(rr);
+	return (ISC_R_EXISTS);
+}
+
+/*%
+ * Utility macro for RR existence checking functions.
+ *
+ * If the variable 'result' has the value ISC_R_EXISTS or
+ * ISC_R_SUCCESS, set *exists to true or false,
+ * respectively, and return success.
+ *
+ * If 'result' has any other value, there was a failure.
+ * Return the failure result code and do not set *exists.
+ *
+ * This would be more readable as "do { if ... } while(0)",
+ * but that form generates tons of warnings on Solaris 2.6.
+ */
+#define RETURN_EXISTENCE_FLAG				\
+	return ((result == ISC_R_EXISTS) ?		\
+		(*exists = true, ISC_R_SUCCESS) :	\
+		((result == ISC_R_SUCCESS) ?		\
+		 (*exists = false, ISC_R_SUCCESS) :	\
+		 result))
+
+/*%
+ * Set '*exists' to true iff an rrset of the given type exists,
+ * to false otherwise.
+ */
+static isc_result_t
+rrset_exists(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
+	     dns_rdatatype_t type, dns_rdatatype_t covers,
+	     bool *exists)
+{
+	isc_result_t result;
+	result = foreach_rr(db, ver, name, type, covers,
+			    rrset_exists_action, NULL);
+	RETURN_EXISTENCE_FLAG;
+}
+
+/*%
+ * Helper function for cname_incompatible_rrset_exists.
+ */
+static isc_result_t
+cname_compatibility_action(void *data, dns_rdataset_t *rrset) {
+	UNUSED(data);
+	if (rrset->type != dns_rdatatype_cname &&
+	    ! dns_rdatatype_isdnssec(rrset->type))
+		return (ISC_R_EXISTS);
+	return (ISC_R_SUCCESS);
+}
+
+/*%
+ * Check whether there is an rrset incompatible with adding a CNAME RR,
+ * i.e., anything but another CNAME (which can be replaced) or a
+ * DNSSEC RR (which can coexist).
+ *
+ * If such an incompatible rrset exists, set '*exists' to true.
+ * Otherwise, set it to false.
+ */
+static isc_result_t
+cname_incompatible_rrset_exists(dns_db_t *db, dns_dbversion_t *ver,
+				dns_name_t *name, bool *exists) {
+	isc_result_t result;
+	result = foreach_rrset(db, ver, name,
+			       cname_compatibility_action, NULL);
+	RETURN_EXISTENCE_FLAG;
+}
+
+/*%
+ * Helper function for rr_count().
+ */
+static isc_result_t
+count_rr_action(void *data, rr_t *rr) {
+	int *countp = data;
+	UNUSED(rr);
+	(*countp)++;
+	return (ISC_R_SUCCESS);
+}
+
+/*%
+ * Count the number of RRs of 'type' belonging to 'name' in 'ver' of 'db'.
+ */
+static isc_result_t
+rr_count(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
+	 dns_rdatatype_t type, dns_rdatatype_t covers, int *countp)
+{
+	*countp = 0;
+	return (foreach_rr(db, ver, name, type, covers,
+			   count_rr_action, countp));
+}
+
+/*%
+ * Context struct and helper function for name_exists().
+ */
+
+static isc_result_t
+name_exists_action(void *data, dns_rdataset_t *rrset) {
+	UNUSED(data);
+	UNUSED(rrset);
+	return (ISC_R_EXISTS);
+}
+
+/*%
+ * Set '*exists' to true iff the given name exists, to false otherwise.
+ */
+static isc_result_t
+name_exists(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
+	    bool *exists)
+{
+	isc_result_t result;
+	result = foreach_rrset(db, ver, name,
+			       name_exists_action, NULL);
+	RETURN_EXISTENCE_FLAG;
+}
+
+/*
+ *	'ssu_check_t' is used to pass the arguments to
+ *	dns_ssutable_checkrules() to the callback function
+ *	ssu_checkrule().
+ */
+typedef struct {
+	/* The ownername of the record to be updated. */
+	dns_name_t *name;
+
+	/* The signature's name if the request was signed. */
+	dns_name_t *signer;
+
+	/* The address of the client. */
+	isc_netaddr_t *addr;
+
+	/* Whether the request was sent via TCP. */
+	bool tcp;
+
+	/* The ssu table to check against. */
+	dns_ssutable_t *table;
+
+	/* the key used for TKEY requests */
+	dst_key_t *key;
+} ssu_check_t;
+
+static isc_result_t
+ssu_checkrule(void *data, dns_rdataset_t *rrset) {
+	ssu_check_t *ssuinfo = data;
+	bool result;
+
+	/*
+	 * If we're deleting all records, it's ok to delete RRSIG and NSEC even
+	 * if we're normally not allowed to.
+	 */
+	if (rrset->type == dns_rdatatype_rrsig ||
+	    rrset->type == dns_rdatatype_nsec)
+		return (ISC_R_SUCCESS);
+	result = dns_ssutable_checkrules2(ssuinfo->table, ssuinfo->signer,
+					  ssuinfo->name, ssuinfo->addr,
+					  ssuinfo->tcp, &ns_g_server->aclenv,
+					  rrset->type, ssuinfo->key);
+	return (result == true ? ISC_R_SUCCESS : ISC_R_FAILURE);
+}
+
+static bool
+ssu_checkall(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
+	     dns_ssutable_t *ssutable, dns_name_t *signer,
+	     isc_netaddr_t *addr, bool tcp, dst_key_t *key)
+{
+	isc_result_t result;
+	ssu_check_t ssuinfo;
+
+	ssuinfo.name = name;
+	ssuinfo.table = ssutable;
+	ssuinfo.signer = signer;
+	ssuinfo.addr = addr;
+	ssuinfo.tcp = tcp;
+	ssuinfo.key = key;
+	result = foreach_rrset(db, ver, name, ssu_checkrule, &ssuinfo);
+	return (result == ISC_R_SUCCESS);
+}
+
+/**************************************************************************/
+/*
+ * Checking of "RRset exists (value dependent)" prerequisites.
+ *
+ * In the RFC2136 section 3.2.5, this is the pseudocode involving
+ * a variable called "temp", a mapping of <name, type> tuples to rrsets.
+ *
+ * Here, we represent the "temp" data structure as (non-minimal) "dns_diff_t"
+ * where each tuple has op==DNS_DIFFOP_EXISTS.
+ */
+
+
+/*%
+ * Append a tuple asserting the existence of the RR with
+ * 'name' and 'rdata' to 'diff'.
+ */
+static isc_result_t
+temp_append(dns_diff_t *diff, dns_name_t *name, dns_rdata_t *rdata) {
+	isc_result_t result;
+	dns_difftuple_t *tuple = NULL;
+
+	REQUIRE(DNS_DIFF_VALID(diff));
+	CHECK(dns_difftuple_create(diff->mctx, DNS_DIFFOP_EXISTS,
+				   name, 0, rdata, &tuple));
+	ISC_LIST_APPEND(diff->tuples, tuple, link);
+ failure:
+	return (result);
+}
+
+/*%
+ * Compare two rdatasets represented as sorted lists of tuples.
+ * All list elements must have the same owner name and type.
+ * Return ISC_R_SUCCESS if the rdatasets are equal, rcode(dns_rcode_nxrrset)
+ * if not.
+ */
+static isc_result_t
+temp_check_rrset(dns_difftuple_t *a, dns_difftuple_t *b) {
+	for (;;) {
+		if (a == NULL || b == NULL)
+			break;
+		INSIST(a->op == DNS_DIFFOP_EXISTS &&
+		       b->op == DNS_DIFFOP_EXISTS);
+		INSIST(a->rdata.type == b->rdata.type);
+		INSIST(dns_name_equal(&a->name, &b->name));
+		if (dns_rdata_casecompare(&a->rdata, &b->rdata) != 0)
+			return (DNS_R_NXRRSET);
+		a = ISC_LIST_NEXT(a, link);
+		b = ISC_LIST_NEXT(b, link);
+	}
+	if (a != NULL || b != NULL)
+		return (DNS_R_NXRRSET);
+	return (ISC_R_SUCCESS);
+}
+
+/*%
+ * A comparison function defining the sorting order for the entries
+ * in the "temp" data structure.  The major sort key is the owner name,
+ * followed by the type and rdata.
+ */
+static int
+temp_order(const void *av, const void *bv) {
+	dns_difftuple_t const * const *ap = av;
+	dns_difftuple_t const * const *bp = bv;
+	dns_difftuple_t const *a = *ap;
+	dns_difftuple_t const *b = *bp;
+	int r;
+	r = dns_name_compare(&a->name, &b->name);
+	if (r != 0)
+		return (r);
+	r = (b->rdata.type - a->rdata.type);
+	if (r != 0)
+		return (r);
+	r = dns_rdata_casecompare(&a->rdata, &b->rdata);
+	return (r);
+}
+
+/*%
+ * Check the "RRset exists (value dependent)" prerequisite information
+ * in 'temp' against the contents of the database 'db'.
+ *
+ * Return ISC_R_SUCCESS if the prerequisites are satisfied,
+ * rcode(dns_rcode_nxrrset) if not.
+ *
+ * 'temp' must be pre-sorted.
+ */
+
+static isc_result_t
+temp_check(isc_mem_t *mctx, dns_diff_t *temp, dns_db_t *db,
+	   dns_dbversion_t *ver, dns_name_t *tmpname, dns_rdatatype_t *typep)
+{
+	isc_result_t result;
+	dns_name_t *name;
+	dns_dbnode_t *node;
+	dns_difftuple_t *t;
+	dns_diff_t trash;
+
+	dns_diff_init(mctx, &trash);
+
+	/*
+	 * For each name and type in the prerequisites,
+	 * construct a sorted rdata list of the corresponding
+	 * database contents, and compare the lists.
+	 */
+	t = ISC_LIST_HEAD(temp->tuples);
+	while (t != NULL) {
+		name = &t->name;
+		(void)dns_name_copy(name, tmpname, NULL);
+		*typep = t->rdata.type;
+
+		/* A new unique name begins here. */
+		node = NULL;
+		result = dns_db_findnode(db, name, false, &node);
+		if (result == ISC_R_NOTFOUND) {
+			dns_diff_clear(&trash);
+			return (DNS_R_NXRRSET);
+		}
+		if (result != ISC_R_SUCCESS) {
+			dns_diff_clear(&trash);
+			return (result);
+		}
+
+		/* A new unique type begins here. */
+		while (t != NULL && dns_name_equal(&t->name, name)) {
+			dns_rdatatype_t type, covers;
+			dns_rdataset_t rdataset;
+			dns_diff_t d_rrs; /* Database RRs with
+						this name and type */
+			dns_diff_t u_rrs; /* Update RRs with
+						this name and type */
+
+			*typep = type = t->rdata.type;
+			if (type == dns_rdatatype_rrsig ||
+			    type == dns_rdatatype_sig)
+				covers = dns_rdata_covers(&t->rdata);
+			else if (type == dns_rdatatype_any) {
+				dns_db_detachnode(db, &node);
+				dns_diff_clear(&trash);
+				return (DNS_R_NXRRSET);
+			} else
+				covers = 0;
+
+			/*
+			 * Collect all database RRs for this name and type
+			 * onto d_rrs and sort them.
+			 */
+			dns_rdataset_init(&rdataset);
+			result = dns_db_findrdataset(db, node, ver, type,
+						     covers, (isc_stdtime_t) 0,
+						     &rdataset, NULL);
+			if (result != ISC_R_SUCCESS) {
+				dns_db_detachnode(db, &node);
+				dns_diff_clear(&trash);
+				return (DNS_R_NXRRSET);
+			}
+
+			dns_diff_init(mctx, &d_rrs);
+			dns_diff_init(mctx, &u_rrs);
+
+			for (result = dns_rdataset_first(&rdataset);
+			     result == ISC_R_SUCCESS;
+			     result = dns_rdataset_next(&rdataset))
+			{
+				dns_rdata_t rdata = DNS_RDATA_INIT;
+				dns_rdataset_current(&rdataset, &rdata);
+				result = temp_append(&d_rrs, name, &rdata);
+				if (result != ISC_R_SUCCESS)
+					goto failure;
+			}
+			if (result != ISC_R_NOMORE)
+				goto failure;
+			result = dns_diff_sort(&d_rrs, temp_order);
+			if (result != ISC_R_SUCCESS)
+				goto failure;
+
+			/*
+			 * Collect all update RRs for this name and type
+			 * onto u_rrs.  No need to sort them here -
+			 * they are already sorted.
+			 */
+			while (t != NULL &&
+			       dns_name_equal(&t->name, name) &&
+			       t->rdata.type == type)
+			{
+				dns_difftuple_t *next =
+					ISC_LIST_NEXT(t, link);
+				ISC_LIST_UNLINK(temp->tuples, t, link);
+				ISC_LIST_APPEND(u_rrs.tuples, t, link);
+				t = next;
+			}
+
+			/* Compare the two sorted lists. */
+			result = temp_check_rrset(ISC_LIST_HEAD(u_rrs.tuples),
+						  ISC_LIST_HEAD(d_rrs.tuples));
+			if (result != ISC_R_SUCCESS)
+				goto failure;
+
+			/*
+			 * We are done with the tuples, but we can't free
+			 * them yet because "name" still points into one
+			 * of them.  Move them on a temporary list.
+			 */
+			ISC_LIST_APPENDLIST(trash.tuples, u_rrs.tuples, link);
+			ISC_LIST_APPENDLIST(trash.tuples, d_rrs.tuples, link);
+			dns_rdataset_disassociate(&rdataset);
+
+			continue;
+
+		    failure:
+			dns_diff_clear(&d_rrs);
+			dns_diff_clear(&u_rrs);
+			dns_diff_clear(&trash);
+			dns_rdataset_disassociate(&rdataset);
+			dns_db_detachnode(db, &node);
+			return (result);
+		}
+
+		dns_db_detachnode(db, &node);
+	}
+
+	dns_diff_clear(&trash);
+	return (ISC_R_SUCCESS);
+}
+
+/**************************************************************************/
+/*
+ * Conditional deletion of RRs.
+ */
+
+/*%
+ * Context structure for delete_if().
+ */
+
+typedef struct {
+	rr_predicate *predicate;
+	dns_db_t *db;
+	dns_dbversion_t *ver;
+	dns_diff_t *diff;
+	dns_name_t *name;
+	dns_rdata_t *update_rr;
+} conditional_delete_ctx_t;
+
+/*%
+ * Predicate functions for delete_if().
+ */
+
+/*%
+ * Return true iff 'db_rr' is neither a SOA nor an NS RR nor
+ * an RRSIG nor an NSEC3PARAM nor a NSEC.
+ */
+static bool
+type_not_soa_nor_ns_p(dns_rdata_t *update_rr, dns_rdata_t *db_rr) {
+	UNUSED(update_rr);
+	return ((db_rr->type != dns_rdatatype_soa &&
+		 db_rr->type != dns_rdatatype_ns &&
+		 db_rr->type != dns_rdatatype_nsec3param &&
+		 db_rr->type != dns_rdatatype_rrsig &&
+		 db_rr->type != dns_rdatatype_nsec) ?
+		true : false);
+}
+
+/*%
+ * Return true iff 'db_rr' is neither a RRSIG nor a NSEC.
+ */
+static bool
+type_not_dnssec(dns_rdata_t *update_rr, dns_rdata_t *db_rr) {
+	UNUSED(update_rr);
+	return ((db_rr->type != dns_rdatatype_rrsig &&
+		 db_rr->type != dns_rdatatype_nsec) ?
+		true : false);
+}
+
+/*%
+ * Return true always.
+ */
+static bool
+true_p(dns_rdata_t *update_rr, dns_rdata_t *db_rr) {
+	UNUSED(update_rr);
+	UNUSED(db_rr);
+	return (true);
+}
+
+/*%
+ * Return true iff the two RRs have identical rdata.
+ */
+static bool
+rr_equal_p(dns_rdata_t *update_rr, dns_rdata_t *db_rr) {
+	/*
+	 * XXXRTH  This is not a problem, but we should consider creating
+	 *         dns_rdata_equal() (that used dns_name_equal()), since it
+	 *         would be faster.  Not a priority.
+	 */
+	return (dns_rdata_casecompare(update_rr, db_rr) == 0 ?
+		true : false);
+}
+
+/*%
+ * Return true iff 'update_rr' should replace 'db_rr' according
+ * to the special RFC2136 rules for CNAME, SOA, and WKS records.
+ *
+ * RFC2136 does not mention NSEC or DNAME, but multiple NSECs or DNAMEs
+ * make little sense, so we replace those, too.
+ *
+ * Additionally replace RRSIG that have been generated by the same key
+ * for the same type.  This simplifies refreshing a offline KSK by not
+ * requiring that the old RRSIG be deleted.  It also simplifies key
+ * rollover by only requiring that the new RRSIG be added.
+ */
+static bool
+replaces_p(dns_rdata_t *update_rr, dns_rdata_t *db_rr) {
+	dns_rdata_rrsig_t updatesig, dbsig;
+	isc_result_t result;
+
+	if (db_rr->type != update_rr->type)
+		return (false);
+	if (db_rr->type == dns_rdatatype_cname)
+		return (true);
+	if (db_rr->type == dns_rdatatype_dname)
+		return (true);
+	if (db_rr->type == dns_rdatatype_soa)
+		return (true);
+	if (db_rr->type == dns_rdatatype_nsec)
+		return (true);
+	if (db_rr->type == dns_rdatatype_rrsig) {
+		/*
+		 * Replace existing RRSIG with the same keyid,
+		 * covered and algorithm.
+		 */
+		result = dns_rdata_tostruct(db_rr, &dbsig, NULL);
+		RUNTIME_CHECK(result == ISC_R_SUCCESS);
+		result = dns_rdata_tostruct(update_rr, &updatesig, NULL);
+		RUNTIME_CHECK(result == ISC_R_SUCCESS);
+		if (dbsig.keyid == updatesig.keyid &&
+		    dbsig.covered == updatesig.covered &&
+		    dbsig.algorithm == updatesig.algorithm)
+			return (true);
+	}
+	if (db_rr->type == dns_rdatatype_wks) {
+		/*
+		 * Compare the address and protocol fields only.  These
+		 * form the first five bytes of the RR data.  Do a
+		 * raw binary comparison; unpacking the WKS RRs using
+		 * dns_rdata_tostruct() might be cleaner in some ways.
+		 */
+		INSIST(db_rr->length >= 5 && update_rr->length >= 5);
+		return (memcmp(db_rr->data, update_rr->data, 5) == 0 ?
+			true : false);
+	}
+
+	if (db_rr->type == dns_rdatatype_nsec3param) {
+		if (db_rr->length != update_rr->length)
+			return (false);
+		INSIST(db_rr->length >= 4 && update_rr->length >= 4);
+		/*
+		 * Replace NSEC3PARAM records that only differ by the
+		 * flags field.
+		 */
+		if (db_rr->data[0] == update_rr->data[0] &&
+		    memcmp(db_rr->data+2, update_rr->data+2,
+			   update_rr->length - 2) == 0)
+			return (true);
+	}
+	return (false);
+}
+
+/*%
+ * Internal helper function for delete_if().
+ */
+static isc_result_t
+delete_if_action(void *data, rr_t *rr) {
+	conditional_delete_ctx_t *ctx = data;
+	if ((*ctx->predicate)(ctx->update_rr, &rr->rdata)) {
+		isc_result_t result;
+		result = update_one_rr(ctx->db, ctx->ver, ctx->diff,
+				       DNS_DIFFOP_DEL, ctx->name,
+				       rr->ttl, &rr->rdata);
+		return (result);
+	} else {
+		return (ISC_R_SUCCESS);
+	}
+}
+
+/*%
+ * Conditionally delete RRs.  Apply 'predicate' to the RRs
+ * specified by 'db', 'ver', 'name', and 'type' (which can
+ * be dns_rdatatype_any to match any type).  Delete those
+ * RRs for which the predicate returns true, and log the
+ * deletions in 'diff'.
+ */
+static isc_result_t
+delete_if(rr_predicate *predicate, dns_db_t *db, dns_dbversion_t *ver,
+	  dns_name_t *name, dns_rdatatype_t type, dns_rdatatype_t covers,
+	  dns_rdata_t *update_rr, dns_diff_t *diff)
+{
+	conditional_delete_ctx_t ctx;
+	ctx.predicate = predicate;
+	ctx.db = db;
+	ctx.ver = ver;
+	ctx.diff = diff;
+	ctx.name = name;
+	ctx.update_rr = update_rr;
+	return (foreach_rr(db, ver, name, type, covers,
+			   delete_if_action, &ctx));
+}
+
+/**************************************************************************/
+
+static isc_result_t
+add_rr_prepare_action(void *data, rr_t *rr) {
+	isc_result_t result = ISC_R_SUCCESS;
+	add_rr_prepare_ctx_t *ctx = data;
+	dns_difftuple_t *tuple = NULL;
+	bool equal, case_equal, ttl_equal;
+
+	/*
+	 * Are the new and old cases equal?
+	 */
+	case_equal = dns_name_caseequal(ctx->name, ctx->oldname);
+
+	/*
+	 * Are the ttl's equal?
+	 */
+	ttl_equal = rr->ttl == ctx->update_rr_ttl;
+
+	/*
+	 * If the update RR is a "duplicate" of a existing RR,
+	 * the update should be silently ignored.
+	 */
+	equal = !dns_rdata_casecompare(&rr->rdata, ctx->update_rr);
+	if (equal && case_equal && ttl_equal) {
+		ctx->ignore_add = true;
+		return (ISC_R_SUCCESS);
+	}
+
+	/*
+	 * If this RR is "equal" to the update RR, it should
+	 * be deleted before the update RR is added.
+	 */
+	if (replaces_p(ctx->update_rr, &rr->rdata)) {
+		CHECK(dns_difftuple_create(ctx->del_diff.mctx, DNS_DIFFOP_DEL,
+					   ctx->oldname, rr->ttl, &rr->rdata,
+					   &tuple));
+		dns_diff_append(&ctx->del_diff, &tuple);
+		return (ISC_R_SUCCESS);
+	}
+
+	/*
+	 * If this RR differs in TTL or case from the update RR,
+	 * its TTL and case must be adjusted.
+	 */
+	if (!ttl_equal || !case_equal) {
+		CHECK(dns_difftuple_create(ctx->del_diff.mctx, DNS_DIFFOP_DEL,
+					   ctx->oldname, rr->ttl, &rr->rdata,
+					   &tuple));
+		dns_diff_append(&ctx->del_diff, &tuple);
+		if (!equal) {
+			CHECK(dns_difftuple_create(ctx->add_diff.mctx,
+						   DNS_DIFFOP_ADD, ctx->name,
+						   ctx->update_rr_ttl,
+						   &rr->rdata, &tuple));
+			dns_diff_append(&ctx->add_diff, &tuple);
+		}
+	}
+ failure:
+	return (result);
+}
+
+/**************************************************************************/
+/*
+ * Miscellaneous subroutines.
+ */
+
+/*%
+ * Extract a single update RR from 'section' of dynamic update message
+ * 'msg', with consistency checking.
+ *
+ * Stores the owner name, rdata, and TTL of the update RR at 'name',
+ * 'rdata', and 'ttl', respectively.
+ */
+static void
+get_current_rr(dns_message_t *msg, dns_section_t section,
+	       dns_rdataclass_t zoneclass, dns_name_t **name,
+	       dns_rdata_t *rdata, dns_rdatatype_t *covers,
+	       dns_ttl_t *ttl, dns_rdataclass_t *update_class)
+{
+	dns_rdataset_t *rdataset;
+	isc_result_t result;
+	dns_message_currentname(msg, section, name);
+	rdataset = ISC_LIST_HEAD((*name)->list);
+	INSIST(rdataset != NULL);
+	INSIST(ISC_LIST_NEXT(rdataset, link) == NULL);
+	*covers = rdataset->covers;
+	*ttl = rdataset->ttl;
+	result = dns_rdataset_first(rdataset);
+	INSIST(result == ISC_R_SUCCESS);
+	dns_rdataset_current(rdataset, rdata);
+	INSIST(dns_rdataset_next(rdataset) == ISC_R_NOMORE);
+	*update_class = rdata->rdclass;
+	rdata->rdclass = zoneclass;
+}
+
+/*%
+ * Increment the SOA serial number of database 'db', version 'ver'.
+ * Replace the SOA record in the database, and log the
+ * change in 'diff'.
+ */
+
+	/*
+	 * XXXRTH  Failures in this routine will be worth logging, when
+	 *         we have a logging system.  Failure to find the zonename
+	 *	   or the SOA rdataset warrant at least an UNEXPECTED_ERROR().
+	 */
+
+static isc_result_t
+update_soa_serial(dns_db_t *db, dns_dbversion_t *ver, dns_diff_t *diff,
+		  isc_mem_t *mctx, dns_updatemethod_t method)
+{
+	dns_difftuple_t *deltuple = NULL;
+	dns_difftuple_t *addtuple = NULL;
+	uint32_t serial;
+	isc_result_t result;
+
+	CHECK(dns_db_createsoatuple(db, ver, mctx, DNS_DIFFOP_DEL, &deltuple));
+	CHECK(dns_difftuple_copy(deltuple, &addtuple));
+	addtuple->op = DNS_DIFFOP_ADD;
+
+	serial = dns_soa_getserial(&addtuple->rdata);
+	serial = dns_update_soaserial(serial, method);
+	dns_soa_setserial(serial, &addtuple->rdata);
+	CHECK(do_one_tuple(&deltuple, db, ver, diff));
+	CHECK(do_one_tuple(&addtuple, db, ver, diff));
+	result = ISC_R_SUCCESS;
+
+ failure:
+	if (addtuple != NULL)
+		dns_difftuple_free(&addtuple);
+	if (deltuple != NULL)
+		dns_difftuple_free(&deltuple);
+	return (result);
+}
+
+/*%
+ * Check that the new SOA record at 'update_rdata' does not
+ * illegally cause the SOA serial number to decrease or stay
+ * unchanged relative to the existing SOA in 'db'.
+ *
+ * Sets '*ok' to true if the update is legal, false if not.
+ *
+ * William King points out that RFC2136 is inconsistent about
+ * the case where the serial number stays unchanged:
+ *
+ *   section 3.4.2.2 requires a server to ignore a SOA update request
+ *   if the serial number on the update SOA is less_than_or_equal to
+ *   the zone SOA serial.
+ *
+ *   section 3.6 requires a server to ignore a SOA update request if
+ *   the serial is less_than the zone SOA serial.
+ *
+ * Paul says 3.4.2.2 is correct.
+ *
+ */
+static isc_result_t
+check_soa_increment(dns_db_t *db, dns_dbversion_t *ver,
+		    dns_rdata_t *update_rdata, bool *ok)
+{
+	uint32_t db_serial;
+	uint32_t update_serial;
+	isc_result_t result;
+
+	update_serial = dns_soa_getserial(update_rdata);
+
+	result = dns_db_getsoaserial(db, ver, &db_serial);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	if (DNS_SERIAL_GE(db_serial, update_serial)) {
+		*ok = false;
+	} else {
+		*ok = true;
+	}
+
+	return (ISC_R_SUCCESS);
+
+}
+
+/**************************************************************************/
+/*%
+ * The actual update code in all its glory.  We try to follow
+ * the RFC2136 pseudocode as closely as possible.
+ */
+
+static isc_result_t
+send_update_event(ns_client_t *client, dns_zone_t *zone) {
+	isc_result_t result = ISC_R_SUCCESS;
+	update_event_t *event = NULL;
+	isc_task_t *zonetask = NULL;
+	ns_client_t *evclient;
+
+	event = (update_event_t *)
+		isc_event_allocate(client->mctx, client, DNS_EVENT_UPDATE,
+				   update_action, NULL, sizeof(*event));
+	if (event == NULL)
+		FAIL(ISC_R_NOMEMORY);
+	event->zone = zone;
+	event->result = ISC_R_SUCCESS;
+
+	evclient = NULL;
+	ns_client_attach(client, &evclient);
+	INSIST(client->nupdates == 0);
+	client->nupdates++;
+	event->ev_arg = evclient;
+
+	dns_zone_gettask(zone, &zonetask);
+	isc_task_send(zonetask, ISC_EVENT_PTR(&event));
+
+ failure:
+	if (event != NULL)
+		isc_event_free(ISC_EVENT_PTR(&event));
+	return (result);
+}
+
+static void
+respond(ns_client_t *client, isc_result_t result) {
+	isc_result_t msg_result;
+
+	msg_result = dns_message_reply(client->message, true);
+	if (msg_result != ISC_R_SUCCESS)
+		goto msg_failure;
+	client->message->rcode = dns_result_torcode(result);
+
+	ns_client_send(client);
+	return;
+
+ msg_failure:
+	isc_log_write(ns_g_lctx, NS_LOGCATEGORY_UPDATE, NS_LOGMODULE_UPDATE,
+		      ISC_LOG_ERROR,
+		      "could not create update response message: %s",
+		      isc_result_totext(msg_result));
+	ns_client_next(client, msg_result);
+}
+
+void
+ns_update_start(ns_client_t *client, isc_result_t sigresult) {
+	dns_message_t *request = client->message;
+	isc_result_t result;
+	dns_name_t *zonename;
+	dns_rdataset_t *zone_rdataset;
+	dns_zone_t *zone = NULL, *raw = NULL;
+
+	/*
+	 * Interpret the zone section.
+	 */
+	result = dns_message_firstname(request, DNS_SECTION_ZONE);
+	if (result != ISC_R_SUCCESS)
+		FAILC(DNS_R_FORMERR, "update zone section empty");
+
+	/*
+	 * The zone section must contain exactly one "question", and
+	 * it must be of type SOA.
+	 */
+	zonename = NULL;
+	dns_message_currentname(request, DNS_SECTION_ZONE, &zonename);
+	zone_rdataset = ISC_LIST_HEAD(zonename->list);
+	if (zone_rdataset->type != dns_rdatatype_soa)
+		FAILC(DNS_R_FORMERR,
+		      "update zone section contains non-SOA");
+	if (ISC_LIST_NEXT(zone_rdataset, link) != NULL)
+		FAILC(DNS_R_FORMERR,
+		      "update zone section contains multiple RRs");
+
+	/* The zone section must have exactly one name. */
+	result = dns_message_nextname(request, DNS_SECTION_ZONE);
+	if (result != ISC_R_NOMORE)
+		FAILC(DNS_R_FORMERR,
+		      "update zone section contains multiple RRs");
+
+	result = dns_zt_find(client->view->zonetable, zonename, 0, NULL,
+			     &zone);
+	if (result != ISC_R_SUCCESS)
+		FAILC(DNS_R_NOTAUTH, "not authoritative for update zone");
+
+	/*
+	 * If there is a raw (unsigned) zone associated with this
+	 * zone then it processes the UPDATE request.
+	 */
+	dns_zone_getraw(zone, &raw);
+	if (raw != NULL) {
+		dns_zone_detach(&zone);
+		dns_zone_attach(raw, &zone);
+		dns_zone_detach(&raw);
+	}
+
+	switch(dns_zone_gettype(zone)) {
+	case dns_zone_master:
+	case dns_zone_dlz:
+		/*
+		 * We can now fail due to a bad signature as we now know
+		 * that we are the master.
+		 */
+		if (sigresult != ISC_R_SUCCESS)
+			FAIL(sigresult);
+		CHECK(send_update_event(client, zone));
+		break;
+	case dns_zone_slave:
+		CHECK(checkupdateacl(client, dns_zone_getforwardacl(zone),
+				     "update forwarding", zonename, true,
+				     false));
+		CHECK(send_forward_event(client, zone));
+		break;
+	default:
+		FAILC(DNS_R_NOTAUTH, "not authoritative for update zone");
+	}
+	return;
+
+ failure:
+	if (result == DNS_R_REFUSED) {
+		INSIST(dns_zone_gettype(zone) == dns_zone_slave);
+		inc_stats(zone, dns_nsstatscounter_updaterej);
+	}
+	/*
+	 * We failed without having sent an update event to the zone.
+	 * We are still in the client task context, so we can
+	 * simply give an error response without switching tasks.
+	 */
+	respond(client, result);
+	if (zone != NULL)
+		dns_zone_detach(&zone);
+}
+
+/*%
+ * DS records are not allowed to exist without corresponding NS records,
+ * RFC 3658, 2.2 Protocol Change,
+ * "DS RRsets MUST NOT appear at non-delegation points or at a zone's apex".
+ */
+
+static isc_result_t
+remove_orphaned_ds(dns_db_t *db, dns_dbversion_t *newver, dns_diff_t *diff) {
+	isc_result_t result;
+	bool ns_exists;
+	dns_difftuple_t *tupple;
+	dns_diff_t temp_diff;
+
+	dns_diff_init(diff->mctx, &temp_diff);
+
+	for (tupple = ISC_LIST_HEAD(diff->tuples);
+	     tupple != NULL;
+	     tupple = ISC_LIST_NEXT(tupple, link)) {
+		if (!((tupple->op == DNS_DIFFOP_DEL &&
+		       tupple->rdata.type == dns_rdatatype_ns) ||
+		      (tupple->op == DNS_DIFFOP_ADD &&
+		       tupple->rdata.type == dns_rdatatype_ds)))
+			continue;
+		CHECK(rrset_exists(db, newver, &tupple->name,
+				   dns_rdatatype_ns, 0, &ns_exists));
+		if (ns_exists &&
+		    !dns_name_equal(&tupple->name, dns_db_origin(db)))
+			continue;
+		CHECK(delete_if(true_p, db, newver, &tupple->name,
+				dns_rdatatype_ds, 0, NULL, &temp_diff));
+	}
+	result = ISC_R_SUCCESS;
+
+ failure:
+	for (tupple = ISC_LIST_HEAD(temp_diff.tuples);
+	     tupple != NULL;
+	     tupple = ISC_LIST_HEAD(temp_diff.tuples)) {
+		ISC_LIST_UNLINK(temp_diff.tuples, tupple, link);
+		dns_diff_appendminimal(diff, &tupple);
+	}
+	return (result);
+}
+
+/*
+ * This implements the post load integrity checks for mx records.
+ */
+static isc_result_t
+check_mx(ns_client_t *client, dns_zone_t *zone,
+	 dns_db_t *db, dns_dbversion_t *newver, dns_diff_t *diff)
+{
+	char tmp[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:123.123.123.123.")];
+	char ownerbuf[DNS_NAME_FORMATSIZE];
+	char namebuf[DNS_NAME_FORMATSIZE];
+	char altbuf[DNS_NAME_FORMATSIZE];
+	dns_difftuple_t *t;
+	dns_fixedname_t fixed;
+	dns_name_t *foundname;
+	dns_rdata_mx_t mx;
+	dns_rdata_t rdata;
+	bool ok = true;
+	bool isaddress;
+	isc_result_t result;
+	struct in6_addr addr6;
+	struct in_addr addr;
+	unsigned int options;
+
+	foundname = dns_fixedname_initname(&fixed);
+	dns_rdata_init(&rdata);
+	options = dns_zone_getoptions(zone);
+
+	for (t = ISC_LIST_HEAD(diff->tuples);
+	     t != NULL;
+	     t = ISC_LIST_NEXT(t, link)) {
+		if (t->op != DNS_DIFFOP_ADD ||
+		    t->rdata.type != dns_rdatatype_mx)
+			continue;
+
+		result = dns_rdata_tostruct(&t->rdata, &mx, NULL);
+		RUNTIME_CHECK(result == ISC_R_SUCCESS);
+		/*
+		 * Check if we will error out if we attempt to reload the
+		 * zone.
+		 */
+		dns_name_format(&mx.mx, namebuf, sizeof(namebuf));
+		dns_name_format(&t->name, ownerbuf, sizeof(ownerbuf));
+		isaddress = false;
+		if ((options & DNS_ZONEOPT_CHECKMX) != 0 &&
+		    strlcpy(tmp, namebuf, sizeof(tmp)) < sizeof(tmp)) {
+			if (tmp[strlen(tmp) - 1] == '.')
+				tmp[strlen(tmp) - 1] = '\0';
+			if (inet_aton(tmp, &addr) == 1 ||
+			    inet_pton(AF_INET6, tmp, &addr6) == 1)
+				isaddress = true;
+		}
+
+		if (isaddress && (options & DNS_ZONEOPT_CHECKMXFAIL) != 0) {
+			update_log(client, zone, ISC_LOG_ERROR,
+				   "%s/MX: '%s': %s",
+				   ownerbuf, namebuf,
+				   dns_result_totext(DNS_R_MXISADDRESS));
+			ok = false;
+		} else if (isaddress) {
+			update_log(client, zone, ISC_LOG_WARNING,
+				   "%s/MX: warning: '%s': %s",
+				   ownerbuf, namebuf,
+				   dns_result_totext(DNS_R_MXISADDRESS));
+		}
+
+		/*
+		 * Check zone integrity checks.
+		 */
+		if ((options & DNS_ZONEOPT_CHECKINTEGRITY) == 0)
+			continue;
+		result = dns_db_find(db, &mx.mx, newver, dns_rdatatype_a,
+				     0, 0, NULL, foundname, NULL, NULL);
+		if (result == ISC_R_SUCCESS)
+			continue;
+
+		if (result == DNS_R_NXRRSET) {
+			result = dns_db_find(db, &mx.mx, newver,
+					     dns_rdatatype_aaaa,
+					     0, 0, NULL, foundname,
+					     NULL, NULL);
+			if (result == ISC_R_SUCCESS)
+				continue;
+		}
+
+		if (result == DNS_R_NXRRSET || result == DNS_R_NXDOMAIN) {
+			update_log(client, zone, ISC_LOG_ERROR,
+				   "%s/MX '%s' has no address records "
+				   "(A or AAAA)", ownerbuf, namebuf);
+			ok = false;
+		} else if (result == DNS_R_CNAME) {
+			update_log(client, zone, ISC_LOG_ERROR,
+				   "%s/MX '%s' is a CNAME (illegal)",
+				   ownerbuf, namebuf);
+			ok = false;
+		} else if (result == DNS_R_DNAME) {
+			dns_name_format(foundname, altbuf, sizeof altbuf);
+			update_log(client, zone, ISC_LOG_ERROR,
+				   "%s/MX '%s' is below a DNAME '%s' (illegal)",
+				   ownerbuf, namebuf, altbuf);
+			ok = false;
+		}
+	}
+	return (ok ? ISC_R_SUCCESS : DNS_R_REFUSED);
+}
+
+static isc_result_t
+rr_exists(dns_db_t *db, dns_dbversion_t *ver, dns_name_t *name,
+	  const dns_rdata_t *rdata, bool *flag)
+{
+	dns_rdataset_t rdataset;
+	dns_dbnode_t *node = NULL;
+	isc_result_t result;
+
+	dns_rdataset_init(&rdataset);
+	if (rdata->type == dns_rdatatype_nsec3)
+		CHECK(dns_db_findnsec3node(db, name, false, &node));
+	else
+		CHECK(dns_db_findnode(db, name, false, &node));
+	result = dns_db_findrdataset(db, node, ver, rdata->type, 0,
+				     (isc_stdtime_t) 0, &rdataset, NULL);
+	if (result == ISC_R_NOTFOUND) {
+		*flag = false;
+		result = ISC_R_SUCCESS;
+		goto failure;
+	}
+
+	for (result = dns_rdataset_first(&rdataset);
+	     result == ISC_R_SUCCESS;
+	     result = dns_rdataset_next(&rdataset)) {
+		dns_rdata_t myrdata = DNS_RDATA_INIT;
+		dns_rdataset_current(&rdataset, &myrdata);
+		if (!dns_rdata_casecompare(&myrdata, rdata))
+			break;
+	}
+	dns_rdataset_disassociate(&rdataset);
+	if (result == ISC_R_SUCCESS) {
+		*flag = true;
+	} else if (result == ISC_R_NOMORE) {
+		*flag = false;
+		result = ISC_R_SUCCESS;
+	}
+
+ failure:
+	if (node != NULL)
+		dns_db_detachnode(db, &node);
+	return (result);
+}
+
+static isc_result_t
+get_iterations(dns_db_t *db, dns_dbversion_t *ver, dns_rdatatype_t privatetype,
+	       unsigned int *iterationsp)
+{
+	dns_dbnode_t *node = NULL;
+	dns_rdata_nsec3param_t nsec3param;
+	dns_rdataset_t rdataset;
+	isc_result_t result;
+	unsigned int iterations = 0;
+
+	dns_rdataset_init(&rdataset);
+
+	result = dns_db_getoriginnode(db, &node);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+	result = dns_db_findrdataset(db, node, ver, dns_rdatatype_nsec3param,
+				     0, (isc_stdtime_t) 0, &rdataset, NULL);
+	if (result == ISC_R_NOTFOUND)
+		goto try_private;
+	if (result != ISC_R_SUCCESS)
+		goto failure;
+
+	for (result = dns_rdataset_first(&rdataset);
+	     result == ISC_R_SUCCESS;
+	     result = dns_rdataset_next(&rdataset)) {
+		dns_rdata_t rdata = DNS_RDATA_INIT;
+		dns_rdataset_current(&rdataset, &rdata);
+		CHECK(dns_rdata_tostruct(&rdata, &nsec3param, NULL));
+		if ((nsec3param.flags & DNS_NSEC3FLAG_REMOVE) != 0)
+			continue;
+		if (nsec3param.iterations > iterations)
+			iterations = nsec3param.iterations;
+	}
+	if (result != ISC_R_NOMORE)
+		goto failure;
+
+	dns_rdataset_disassociate(&rdataset);
+
+ try_private:
+	if (privatetype == 0)
+		goto success;
+
+	result = dns_db_findrdataset(db, node, ver, privatetype,
+				     0, (isc_stdtime_t) 0, &rdataset, NULL);
+	if (result == ISC_R_NOTFOUND)
+		goto success;
+	if (result != ISC_R_SUCCESS)
+		goto failure;
+
+	for (result = dns_rdataset_first(&rdataset);
+	     result == ISC_R_SUCCESS;
+	     result = dns_rdataset_next(&rdataset)) {
+		unsigned char buf[DNS_NSEC3PARAM_BUFFERSIZE];
+		dns_rdata_t private = DNS_RDATA_INIT;
+		dns_rdata_t rdata = DNS_RDATA_INIT;
+
+		dns_rdataset_current(&rdataset, &rdata);
+		if (!dns_nsec3param_fromprivate(&private, &rdata,
+						buf, sizeof(buf)))
+			continue;
+		CHECK(dns_rdata_tostruct(&rdata, &nsec3param, NULL));
+		if ((nsec3param.flags & DNS_NSEC3FLAG_REMOVE) != 0)
+			continue;
+		if (nsec3param.iterations > iterations)
+			iterations = nsec3param.iterations;
+	}
+	if (result != ISC_R_NOMORE)
+		goto failure;
+
+ success:
+	*iterationsp = iterations;
+	result = ISC_R_SUCCESS;
+
+ failure:
+	if (node != NULL)
+		dns_db_detachnode(db, &node);
+	if (dns_rdataset_isassociated(&rdataset))
+		dns_rdataset_disassociate(&rdataset);
+	return (result);
+}
+
+/*
+ * Prevent the zone entering a inconsistent state where
+ * NSEC only DNSKEYs are present with NSEC3 chains.
+ */
+static isc_result_t
+check_dnssec(ns_client_t *client, dns_zone_t *zone, dns_db_t *db,
+	     dns_dbversion_t *ver, dns_diff_t *diff)
+{
+	dns_difftuple_t *tuple;
+	bool nseconly = false, nsec3 = false;
+	isc_result_t result;
+	unsigned int iterations = 0, max;
+	dns_rdatatype_t privatetype = dns_zone_getprivatetype(zone);
+
+	/* Scan the tuples for an NSEC-only DNSKEY or an NSEC3PARAM */
+	for (tuple = ISC_LIST_HEAD(diff->tuples);
+	     tuple != NULL;
+	     tuple = ISC_LIST_NEXT(tuple, link)) {
+		if (tuple->op != DNS_DIFFOP_ADD)
+			continue;
+
+		if (tuple->rdata.type == dns_rdatatype_dnskey) {
+			uint8_t alg;
+			alg = tuple->rdata.data[3];
+			if (alg == DST_ALG_RSAMD5 || alg == DST_ALG_RSASHA1 ||
+			    alg == DST_ALG_DSA || alg == DST_ALG_ECC) {
+				nseconly = true;
+				break;
+			}
+		} else if (tuple->rdata.type == dns_rdatatype_nsec3param) {
+			nsec3 = true;
+			break;
+		}
+	}
+
+	/* Check existing DB for NSEC-only DNSKEY */
+	if (!nseconly) {
+		result = dns_nsec_nseconly(db, ver, &nseconly);
+
+		/*
+		 * An NSEC3PARAM update can proceed without a DNSKEY (it
+		 * will trigger a delayed change), so we can ignore
+		 * ISC_R_NOTFOUND here.
+		 */
+		if (result == ISC_R_NOTFOUND)
+			result = ISC_R_SUCCESS;
+
+		CHECK(result);
+	}
+
+	/* Check existing DB for NSEC3 */
+	if (!nsec3)
+		CHECK(dns_nsec3_activex(db, ver, false,
+					privatetype, &nsec3));
+
+	/* Refuse to allow NSEC3 with NSEC-only keys */
+	if (nseconly && nsec3) {
+		update_log(client, zone, ISC_LOG_ERROR,
+			   "NSEC only DNSKEYs and NSEC3 chains not allowed");
+		result = DNS_R_REFUSED;
+		goto failure;
+	}
+
+	/* Verify NSEC3 params */
+	CHECK(get_iterations(db, ver, privatetype, &iterations));
+	CHECK(dns_nsec3_maxiterations(db, ver, client->mctx, &max));
+	if (max != 0 && iterations > max) {
+		update_log(client, zone, ISC_LOG_ERROR,
+			   "too many NSEC3 iterations (%u) for "
+			   "weakest DNSKEY (%u)", iterations, max);
+		result = DNS_R_REFUSED;
+		goto failure;
+	}
+
+ failure:
+	return (result);
+}
+
+/*
+ * Delay NSEC3PARAM changes as they need to be applied to the whole zone.
+ */
+static isc_result_t
+add_nsec3param_records(ns_client_t *client, dns_zone_t *zone, dns_db_t *db,
+		       dns_dbversion_t *ver, dns_diff_t *diff)
+{
+	isc_result_t result = ISC_R_SUCCESS;
+	dns_difftuple_t *tuple, *newtuple = NULL, *next;
+	dns_rdata_t rdata = DNS_RDATA_INIT;
+	unsigned char buf[DNS_NSEC3PARAM_BUFFERSIZE + 1];
+	dns_diff_t temp_diff;
+	dns_diffop_t op;
+	bool flag;
+	dns_name_t *name = dns_zone_getorigin(zone);
+	dns_rdatatype_t privatetype = dns_zone_getprivatetype(zone);
+	uint32_t ttl = 0;
+	bool ttl_good = false;
+
+	update_log(client, zone, ISC_LOG_DEBUG(3),
+		    "checking for NSEC3PARAM changes");
+
+	dns_diff_init(diff->mctx, &temp_diff);
+
+	/*
+	 * Extract NSEC3PARAM tuples from list.
+	 */
+	for (tuple = ISC_LIST_HEAD(diff->tuples);
+	     tuple != NULL;
+	     tuple = next) {
+
+		next = ISC_LIST_NEXT(tuple, link);
+
+		if (tuple->rdata.type != dns_rdatatype_nsec3param ||
+		    !dns_name_equal(name, &tuple->name))
+			continue;
+		ISC_LIST_UNLINK(diff->tuples, tuple, link);
+		ISC_LIST_APPEND(temp_diff.tuples, tuple, link);
+	}
+
+	/*
+	 * Extract TTL changes pairs, we don't need to convert these to
+	 * delayed changes.
+	 */
+	for (tuple = ISC_LIST_HEAD(temp_diff.tuples);
+	     tuple != NULL; tuple = next) {
+		if (tuple->op == DNS_DIFFOP_ADD) {
+			if (!ttl_good) {
+				/*
+				 * Any adds here will contain the final
+				 * NSEC3PARAM RRset TTL.
+				 */
+				ttl = tuple->ttl;
+				ttl_good = true;
+			}
+			/*
+			 * Walk the temp_diff list looking for the
+			 * corresponding delete.
+			 */
+			next = ISC_LIST_HEAD(temp_diff.tuples);
+			while (next != NULL) {
+				unsigned char *next_data = next->rdata.data;
+				unsigned char *tuple_data = tuple->rdata.data;
+				if (next->op == DNS_DIFFOP_DEL &&
+				    next->rdata.length == tuple->rdata.length &&
+				    !memcmp(next_data, tuple_data,
+					    next->rdata.length)) {
+					ISC_LIST_UNLINK(temp_diff.tuples, next,
+							link);
+					ISC_LIST_APPEND(diff->tuples, next,
+							link);
+					break;
+				}
+				next = ISC_LIST_NEXT(next, link);
+			}
+			/*
+			 * If we have not found a pair move onto the next
+			 * tuple.
+			 */
+			if (next == NULL) {
+				next = ISC_LIST_NEXT(tuple, link);
+				continue;
+			}
+			/*
+			 * Find the next tuple to be processed before
+			 * unlinking then complete moving the pair to 'diff'.
+			 */
+			next = ISC_LIST_NEXT(tuple, link);
+			ISC_LIST_UNLINK(temp_diff.tuples, tuple, link);
+			ISC_LIST_APPEND(diff->tuples, tuple, link);
+		} else
+			next = ISC_LIST_NEXT(tuple, link);
+	}
+
+	/*
+	 * Preserve any ongoing changes from a BIND 9.6.x upgrade.
+	 *
+	 * Any NSEC3PARAM records with flags other than OPTOUT named
+	 * in managing and should not be touched so revert such changes
+	 * taking into account any TTL change of the NSEC3PARAM RRset.
+	 */
+	for (tuple = ISC_LIST_HEAD(temp_diff.tuples);
+	     tuple != NULL; tuple = next) {
+		next = ISC_LIST_NEXT(tuple, link);
+		if ((tuple->rdata.data[1] & ~DNS_NSEC3FLAG_OPTOUT) != 0) {
+			/*
+			 * If we havn't had any adds then the tuple->ttl must
+			 * be the original ttl and should be used for any
+			 * future changes.
+			 */
+			if (!ttl_good) {
+				ttl = tuple->ttl;
+				ttl_good = true;
+			}
+			op = (tuple->op == DNS_DIFFOP_DEL) ?
+			     DNS_DIFFOP_ADD : DNS_DIFFOP_DEL;
+			CHECK(dns_difftuple_create(diff->mctx, op, name,
+						   ttl, &tuple->rdata,
+						   &newtuple));
+			CHECK(do_one_tuple(&newtuple, db, ver, diff));
+			ISC_LIST_UNLINK(temp_diff.tuples, tuple, link);
+			dns_diff_appendminimal(diff, &tuple);
+		}
+	}
+
+	/*
+	 * We now have just the actual changes to the NSEC3PARAM RRset.
+	 * Convert the adds to delayed adds and the deletions into delayed
+	 * deletions.
+	 */
+	for (tuple = ISC_LIST_HEAD(temp_diff.tuples);
+	     tuple != NULL; tuple = next) {
+		/*
+		 * If we havn't had any adds then the tuple->ttl must be the
+		 * original ttl and should be used for any future changes.
+		 */
+		if (!ttl_good) {
+			ttl = tuple->ttl;
+			ttl_good = true;
+		}
+		if (tuple->op == DNS_DIFFOP_ADD) {
+			bool nseconly = false;
+
+			/*
+			 * Look for any deletes which match this ADD ignoring
+			 * flags.  We don't need to explictly remove them as
+			 * they will be removed a side effect of processing
+			 * the add.
+			 */
+			next = ISC_LIST_HEAD(temp_diff.tuples);
+			while (next != NULL) {
+				unsigned char *next_data = next->rdata.data;
+				unsigned char *tuple_data = tuple->rdata.data;
+				if (next->op != DNS_DIFFOP_DEL ||
+				    next->rdata.length != tuple->rdata.length ||
+				    next_data[0] != tuple_data[0] ||
+				    next_data[2] != tuple_data[2] ||
+				    next_data[3] != tuple_data[3] ||
+				    memcmp(next_data + 4, tuple_data + 4,
+					   tuple->rdata.length - 4)) {
+					next = ISC_LIST_NEXT(next, link);
+					continue;
+				}
+				ISC_LIST_UNLINK(temp_diff.tuples, next, link);
+				ISC_LIST_APPEND(diff->tuples, next, link);
+				next = ISC_LIST_HEAD(temp_diff.tuples);
+			}
+
+			/*
+			 * Create a private-type record to signal that
+			 * we want a delayed NSEC3 chain add/delete
+			 */
+			dns_nsec3param_toprivate(&tuple->rdata, &rdata,
+						 privatetype, buf, sizeof(buf));
+			buf[2] |= DNS_NSEC3FLAG_CREATE;
+
+			/*
+			 * If the zone is not currently capable of
+			 * supporting an NSEC3 chain, then we set the
+			 * INITIAL flag to indicate that these parameters
+			 * are to be used later.
+			 */
+			result = dns_nsec_nseconly(db, ver, &nseconly);
+			if (result == ISC_R_NOTFOUND || nseconly)
+				buf[2] |= DNS_NSEC3FLAG_INITIAL;
+
+			/*
+			 * See if this CREATE request already exists.
+			 */
+			CHECK(rr_exists(db, ver, name, &rdata, &flag));
+
+			if (!flag) {
+				CHECK(dns_difftuple_create(diff->mctx,
+							   DNS_DIFFOP_ADD,
+							   name, 0, &rdata,
+							   &newtuple));
+				CHECK(do_one_tuple(&newtuple, db, ver, diff));
+			}
+
+			/*
+			 * Remove any existing CREATE request to add an
+			 * otherwise indentical chain with a reversed
+			 * OPTOUT state.
+			 */
+			buf[2] ^= DNS_NSEC3FLAG_OPTOUT;
+			CHECK(rr_exists(db, ver, name, &rdata, &flag));
+
+			if (flag) {
+				CHECK(dns_difftuple_create(diff->mctx,
+							   DNS_DIFFOP_DEL,
+							   name, 0, &rdata,
+							   &newtuple));
+				CHECK(do_one_tuple(&newtuple, db, ver, diff));
+			}
+
+			/*
+			 * Find the next tuple to be processed and remove the
+			 * temporary add record.
+			 */
+			next = ISC_LIST_NEXT(tuple, link);
+			CHECK(dns_difftuple_create(diff->mctx, DNS_DIFFOP_DEL,
+						   name, ttl, &tuple->rdata,
+						   &newtuple));
+			CHECK(do_one_tuple(&newtuple, db, ver, diff));
+			ISC_LIST_UNLINK(temp_diff.tuples, tuple, link);
+			dns_diff_appendminimal(diff, &tuple);
+			dns_rdata_reset(&rdata);
+		} else
+			next = ISC_LIST_NEXT(tuple, link);
+	}
+
+	for (tuple = ISC_LIST_HEAD(temp_diff.tuples);
+	     tuple != NULL; tuple = next) {
+
+		INSIST(ttl_good);
+
+		next = ISC_LIST_NEXT(tuple, link);
+		/*
+		 * See if we already have a REMOVE request in progress.
+		 */
+		dns_nsec3param_toprivate(&tuple->rdata, &rdata, privatetype,
+					 buf, sizeof(buf));
+
+		buf[2] |= DNS_NSEC3FLAG_REMOVE | DNS_NSEC3FLAG_NONSEC;
+
+		CHECK(rr_exists(db, ver, name, &rdata, &flag));
+		if (!flag) {
+			buf[2] &= ~DNS_NSEC3FLAG_NONSEC;
+			CHECK(rr_exists(db, ver, name, &rdata, &flag));
+		}
+
+		if (!flag) {
+			CHECK(dns_difftuple_create(diff->mctx, DNS_DIFFOP_ADD,
+						   name, 0, &rdata, &newtuple));
+			CHECK(do_one_tuple(&newtuple, db, ver, diff));
+		}
+		CHECK(dns_difftuple_create(diff->mctx, DNS_DIFFOP_ADD, name,
+					   ttl, &tuple->rdata, &newtuple));
+		CHECK(do_one_tuple(&newtuple, db, ver, diff));
+		ISC_LIST_UNLINK(temp_diff.tuples, tuple, link);
+		dns_diff_appendminimal(diff, &tuple);
+		dns_rdata_reset(&rdata);
+	}
+
+	result = ISC_R_SUCCESS;
+ failure:
+	dns_diff_clear(&temp_diff);
+	return (result);
+}
+
+static isc_result_t
+rollback_private(dns_db_t *db, dns_rdatatype_t privatetype,
+		 dns_dbversion_t *ver, dns_diff_t *diff)
+{
+	dns_diff_t temp_diff;
+	dns_diffop_t op;
+	dns_difftuple_t *tuple, *newtuple = NULL, *next;
+	dns_name_t *name = dns_db_origin(db);
+	isc_mem_t *mctx = diff->mctx;
+	isc_result_t result;
+
+	if (privatetype == 0)
+		return (ISC_R_SUCCESS);
+
+	dns_diff_init(mctx, &temp_diff);
+
+	/*
+	 * Extract the changes to be rolled back.
+	 */
+	for (tuple = ISC_LIST_HEAD(diff->tuples);
+	     tuple != NULL; tuple = next) {
+
+		next = ISC_LIST_NEXT(tuple, link);
+
+		if (tuple->rdata.type != privatetype ||
+		    !dns_name_equal(name, &tuple->name))
+			continue;
+
+		/*
+		 * Allow records which indicate that a zone has been
+		 * signed with a DNSKEY to be removed.
+		 */
+		if (tuple->op == DNS_DIFFOP_DEL &&
+		    tuple->rdata.length == 5 &&
+		    tuple->rdata.data[0] != 0 &&
+		    tuple->rdata.data[4] != 0)
+			continue;
+
+		ISC_LIST_UNLINK(diff->tuples, tuple, link);
+		ISC_LIST_PREPEND(temp_diff.tuples, tuple, link);
+	}
+
+	/*
+	 * Rollback the changes.
+	 */
+	while ((tuple = ISC_LIST_HEAD(temp_diff.tuples)) != NULL) {
+		op = (tuple->op == DNS_DIFFOP_DEL) ?
+		      DNS_DIFFOP_ADD : DNS_DIFFOP_DEL;
+		CHECK(dns_difftuple_create(mctx, op, name, tuple->ttl,
+					   &tuple->rdata, &newtuple));
+		CHECK(do_one_tuple(&newtuple, db, ver, &temp_diff));
+	}
+	result = ISC_R_SUCCESS;
+
+ failure:
+	dns_diff_clear(&temp_diff);
+	return (result);
+}
+
+/*
+ * Add records to cause the delayed signing of the zone by added DNSKEY
+ * to remove the RRSIG records generated by a deleted DNSKEY.
+ */
+static isc_result_t
+add_signing_records(dns_db_t *db, dns_rdatatype_t privatetype,
+		    dns_dbversion_t *ver, dns_diff_t *diff)
+{
+	dns_difftuple_t *tuple, *newtuple = NULL, *next;
+	dns_rdata_dnskey_t dnskey;
+	dns_rdata_t rdata = DNS_RDATA_INIT;
+	bool flag;
+	isc_region_t r;
+	isc_result_t result = ISC_R_SUCCESS;
+	uint16_t keyid;
+	unsigned char buf[5];
+	dns_name_t *name = dns_db_origin(db);
+	dns_diff_t temp_diff;
+
+	dns_diff_init(diff->mctx, &temp_diff);
+
+	/*
+	 * Extract the DNSKEY tuples from the list.
+	 */
+	for (tuple = ISC_LIST_HEAD(diff->tuples);
+	     tuple != NULL; tuple = next) {
+
+		next = ISC_LIST_NEXT(tuple, link);
+
+		if (tuple->rdata.type != dns_rdatatype_dnskey)
+			continue;
+
+		ISC_LIST_UNLINK(diff->tuples, tuple, link);
+		ISC_LIST_APPEND(temp_diff.tuples, tuple, link);
+	}
+
+	/*
+	 * Extract TTL changes pairs, we don't need signing records for these.
+	 */
+	for (tuple = ISC_LIST_HEAD(temp_diff.tuples);
+	     tuple != NULL; tuple = next) {
+		if (tuple->op == DNS_DIFFOP_ADD) {
+			/*
+			 * Walk the temp_diff list looking for the
+			 * corresponding delete.
+			 */
+			next = ISC_LIST_HEAD(temp_diff.tuples);
+			while (next != NULL) {
+				unsigned char *next_data = next->rdata.data;
+				unsigned char *tuple_data = tuple->rdata.data;
+				if (next->op == DNS_DIFFOP_DEL &&
+				    dns_name_equal(&tuple->name, &next->name) &&
+				    next->rdata.length == tuple->rdata.length &&
+				    !memcmp(next_data, tuple_data,
+					    next->rdata.length)) {
+					ISC_LIST_UNLINK(temp_diff.tuples, next,
+							link);
+					ISC_LIST_APPEND(diff->tuples, next,
+							link);
+					break;
+				}
+				next = ISC_LIST_NEXT(next, link);
+			}
+			/*
+			 * If we have not found a pair move onto the next
+			 * tuple.
+			 */
+			if (next == NULL) {
+				next = ISC_LIST_NEXT(tuple, link);
+				continue;
+			}
+			/*
+			 * Find the next tuple to be processed before
+			 * unlinking then complete moving the pair to 'diff'.
+			 */
+			next = ISC_LIST_NEXT(tuple, link);
+			ISC_LIST_UNLINK(temp_diff.tuples, tuple, link);
+			ISC_LIST_APPEND(diff->tuples, tuple, link);
+		} else
+			next = ISC_LIST_NEXT(tuple, link);
+	}
+
+	/*
+	 * Process the remaining DNSKEY entries.
+	 */
+	for (tuple = ISC_LIST_HEAD(temp_diff.tuples);
+	     tuple != NULL;
+	     tuple = ISC_LIST_HEAD(temp_diff.tuples)) {
+
+		ISC_LIST_UNLINK(temp_diff.tuples, tuple, link);
+		ISC_LIST_APPEND(diff->tuples, tuple, link);
+
+		result = dns_rdata_tostruct(&tuple->rdata, &dnskey, NULL);
+		RUNTIME_CHECK(result == ISC_R_SUCCESS);
+		if ((dnskey.flags &
+		     (DNS_KEYFLAG_OWNERMASK|DNS_KEYTYPE_NOAUTH))
+			 != DNS_KEYOWNER_ZONE)
+			continue;
+
+		dns_rdata_toregion(&tuple->rdata, &r);
+
+		keyid = dst_region_computeid(&r, dnskey.algorithm);
+
+		buf[0] = dnskey.algorithm;
+		buf[1] = (keyid & 0xff00) >> 8;
+		buf[2] = (keyid & 0xff);
+		buf[3] = (tuple->op == DNS_DIFFOP_ADD) ? 0 : 1;
+		buf[4] = 0;
+		rdata.data = buf;
+		rdata.length = sizeof(buf);
+		rdata.type = privatetype;
+		rdata.rdclass = tuple->rdata.rdclass;
+
+		CHECK(rr_exists(db, ver, name, &rdata, &flag));
+		if (flag)
+			continue;
+		CHECK(dns_difftuple_create(diff->mctx, DNS_DIFFOP_ADD,
+					   name, 0, &rdata, &newtuple));
+		CHECK(do_one_tuple(&newtuple, db, ver, diff));
+		INSIST(newtuple == NULL);
+		/*
+		 * Remove any record which says this operation has already
+		 * completed.
+		 */
+		buf[4] = 1;
+		CHECK(rr_exists(db, ver, name, &rdata, &flag));
+		if (flag) {
+			CHECK(dns_difftuple_create(diff->mctx, DNS_DIFFOP_DEL,
+						   name, 0, &rdata, &newtuple));
+			CHECK(do_one_tuple(&newtuple, db, ver, diff));
+			INSIST(newtuple == NULL);
+		}
+	}
+
+ failure:
+	dns_diff_clear(&temp_diff);
+	return (result);
+}
+
+static bool
+isdnssec(dns_db_t *db, dns_dbversion_t *ver, dns_rdatatype_t privatetype) {
+	isc_result_t result;
+	bool build_nsec, build_nsec3;
+
+	if (dns_db_issecure(db))
+		return (true);
+
+	result = dns_private_chains(db, ver, privatetype,
+				    &build_nsec, &build_nsec3);
+	RUNTIME_CHECK(result == ISC_R_SUCCESS);
+	return (build_nsec || build_nsec3);
+}
+
+static void
+update_action(isc_task_t *task, isc_event_t *event) {
+	update_event_t *uev = (update_event_t *) event;
+	dns_zone_t *zone = uev->zone;
+	ns_client_t *client = (ns_client_t *)event->ev_arg;
+	isc_result_t result;
+	dns_db_t *db = NULL;
+	dns_dbversion_t *oldver = NULL;
+	dns_dbversion_t *ver = NULL;
+	dns_diff_t diff;	/* Pending updates. */
+	dns_diff_t temp;	/* Pending RR existence assertions. */
+	bool soa_serial_changed = false;
+	isc_mem_t *mctx = client->mctx;
+	dns_rdatatype_t covers;
+	dns_message_t *request = client->message;
+	dns_rdataclass_t zoneclass;
+	dns_name_t *zonename;
+	dns_ssutable_t *ssutable = NULL;
+	dns_fixedname_t tmpnamefixed;
+	dns_name_t *tmpname = NULL;
+	unsigned int options, options2;
+	dns_difftuple_t *tuple;
+	dns_rdata_dnskey_t dnskey;
+	bool had_dnskey;
+	dns_rdatatype_t privatetype = dns_zone_getprivatetype(zone);
+	dns_ttl_t maxttl = 0;
+	uint32_t maxrecords;
+	uint64_t records;
+
+	INSIST(event->ev_type == DNS_EVENT_UPDATE);
+
+	dns_diff_init(mctx, &diff);
+	dns_diff_init(mctx, &temp);
+
+	CHECK(dns_zone_getdb(zone, &db));
+	zonename = dns_db_origin(db);
+	zoneclass = dns_db_class(db);
+	dns_zone_getssutable(zone, &ssutable);
+
+	/*
+	 * Update message processing can leak record existance information
+	 * so check that we are allowed to query this zone.  Additionally
+	 * if we would refuse all updates for this zone we bail out here.
+	 */
+	CHECK(checkqueryacl(client, dns_zone_getqueryacl(zone), zonename,
+			    dns_zone_getupdateacl(zone), ssutable));
+
+	/*
+	 * Get old and new versions now that queryacl has been checked.
+	 */
+	dns_db_currentversion(db, &oldver);
+	CHECK(dns_db_newversion(db, &ver));
+
+	/*
+	 * Check prerequisites.
+	 */
+
+	for (result = dns_message_firstname(request, DNS_SECTION_PREREQUISITE);
+	     result == ISC_R_SUCCESS;
+	     result = dns_message_nextname(request, DNS_SECTION_PREREQUISITE))
+	{
+		dns_name_t *name = NULL;
+		dns_rdata_t rdata = DNS_RDATA_INIT;
+		dns_ttl_t ttl;
+		dns_rdataclass_t update_class;
+		bool flag;
+
+		get_current_rr(request, DNS_SECTION_PREREQUISITE, zoneclass,
+			       &name, &rdata, &covers, &ttl, &update_class);
+
+		if (ttl != 0)
+			PREREQFAILC(DNS_R_FORMERR,
+				    "prerequisite TTL is not zero");
+
+		if (! dns_name_issubdomain(name, zonename))
+			PREREQFAILN(DNS_R_NOTZONE, name,
+				    "prerequisite name is out of zone");
+
+		if (update_class == dns_rdataclass_any) {
+			if (rdata.length != 0)
+				PREREQFAILC(DNS_R_FORMERR,
+				      "class ANY prerequisite "
+				      "RDATA is not empty");
+			if (rdata.type == dns_rdatatype_any) {
+				CHECK(name_exists(db, ver, name, &flag));
+				if (! flag) {
+					PREREQFAILN(DNS_R_NXDOMAIN, name,
+						    "'name in use' "
+						    "prerequisite not "
+						    "satisfied");
+				}
+			} else {
+				CHECK(rrset_exists(db, ver, name,
+						   rdata.type, covers, &flag));
+				if (! flag) {
+					/* RRset does not exist. */
+					PREREQFAILNT(DNS_R_NXRRSET, name, rdata.type,
+					"'rrset exists (value independent)' "
+					"prerequisite not satisfied");
+				}
+			}
+		} else if (update_class == dns_rdataclass_none) {
+			if (rdata.length != 0)
+				PREREQFAILC(DNS_R_FORMERR,
+					    "class NONE prerequisite "
+					    "RDATA is not empty");
+			if (rdata.type == dns_rdatatype_any) {
+				CHECK(name_exists(db, ver, name, &flag));
+				if (flag) {
+					PREREQFAILN(DNS_R_YXDOMAIN, name,
+						    "'name not in use' "
+						    "prerequisite not "
+						    "satisfied");
+				}
+			} else {
+				CHECK(rrset_exists(db, ver, name,
+						   rdata.type, covers, &flag));
+				if (flag) {
+					/* RRset exists. */
+					PREREQFAILNT(DNS_R_YXRRSET, name,
+						     rdata.type,
+						     "'rrset does not exist' "
+						     "prerequisite not "
+						     "satisfied");
+				}
+			}
+		} else if (update_class == zoneclass) {
+			/* "temp<rr.name, rr.type> += rr;" */
+			result = temp_append(&temp, name, &rdata);
+			if (result != ISC_R_SUCCESS) {
+				UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "temp entry creation failed: %s",
+						 dns_result_totext(result));
+				FAIL(ISC_R_UNEXPECTED);
+			}
+		} else {
+			PREREQFAILC(DNS_R_FORMERR, "malformed prerequisite");
+		}
+	}
+	if (result != ISC_R_NOMORE)
+		FAIL(result);
+
+	/*
+	 * Perform the final check of the "rrset exists (value dependent)"
+	 * prerequisites.
+	 */
+	if (ISC_LIST_HEAD(temp.tuples) != NULL) {
+		dns_rdatatype_t type;
+
+		/*
+		 * Sort the prerequisite records by owner name,
+		 * type, and rdata.
+		 */
+		result = dns_diff_sort(&temp, temp_order);
+		if (result != ISC_R_SUCCESS)
+			FAILC(result, "'RRset exists (value dependent)' "
+			      "prerequisite not satisfied");
+
+		tmpname = dns_fixedname_initname(&tmpnamefixed);
+		result = temp_check(mctx, &temp, db, ver, tmpname, &type);
+		if (result != ISC_R_SUCCESS)
+			FAILNT(result, tmpname, type,
+			       "'RRset exists (value dependent)' "
+			       "prerequisite not satisfied");
+	}
+
+	update_log(client, zone, LOGLEVEL_DEBUG,
+		   "prerequisites are OK");
+
+	/*
+	 * Check Requestor's Permissions.  It seems a bit silly to do this
+	 * only after prerequisite testing, but that is what RFC2136 says.
+	 */
+	if (ssutable == NULL)
+		CHECK(checkupdateacl(client, dns_zone_getupdateacl(zone),
+				     "update", zonename, false, false));
+	else if (client->signer == NULL && !TCPCLIENT(client))
+		CHECK(checkupdateacl(client, NULL, "update", zonename,
+				     false, true));
+
+	if (dns_zone_getupdatedisabled(zone))
+		FAILC(DNS_R_REFUSED, "dynamic update temporarily disabled "
+				     "because the zone is frozen.  Use "
+				     "'rndc thaw' to re-enable updates.");
+
+	/*
+	 * Perform the Update Section Prescan.
+	 */
+
+	for (result = dns_message_firstname(request, DNS_SECTION_UPDATE);
+	     result == ISC_R_SUCCESS;
+	     result = dns_message_nextname(request, DNS_SECTION_UPDATE))
+	{
+		dns_name_t *name = NULL;
+		dns_rdata_t rdata = DNS_RDATA_INIT;
+		dns_ttl_t ttl;
+		dns_rdataclass_t update_class;
+		get_current_rr(request, DNS_SECTION_UPDATE, zoneclass,
+			       &name, &rdata, &covers, &ttl, &update_class);
+
+		if (! dns_name_issubdomain(name, zonename))
+			FAILC(DNS_R_NOTZONE,
+			      "update RR is outside zone");
+		if (update_class == zoneclass) {
+			/*
+			 * Check for meta-RRs.  The RFC2136 pseudocode says
+			 * check for ANY|AXFR|MAILA|MAILB, but the text adds
+			 * "or any other QUERY metatype"
+			 */
+			if (dns_rdatatype_ismeta(rdata.type)) {
+				FAILC(DNS_R_FORMERR,
+				      "meta-RR in update");
+			}
+			result = dns_zone_checknames(zone, name, &rdata);
+			if (result != ISC_R_SUCCESS)
+				FAIL(DNS_R_REFUSED);
+		} else if (update_class == dns_rdataclass_any) {
+			if (ttl != 0 || rdata.length != 0 ||
+			    (dns_rdatatype_ismeta(rdata.type) &&
+			     rdata.type != dns_rdatatype_any))
+				FAILC(DNS_R_FORMERR,
+				      "meta-RR in update");
+		} else if (update_class == dns_rdataclass_none) {
+			if (ttl != 0 ||
+			    dns_rdatatype_ismeta(rdata.type))
+				FAILC(DNS_R_FORMERR,
+				      "meta-RR in update");
+		} else {
+			update_log(client, zone, ISC_LOG_WARNING,
+				   "update RR has incorrect class %d",
+				   update_class);
+			FAIL(DNS_R_FORMERR);
+		}
+
+		/*
+		 * draft-ietf-dnsind-simple-secure-update-01 says
+		 * "Unlike traditional dynamic update, the client
+		 * is forbidden from updating NSEC records."
+		 */
+		if (rdata.type == dns_rdatatype_nsec3) {
+			FAILC(DNS_R_REFUSED,
+			      "explicit NSEC3 updates are not allowed "
+			      "in secure zones");
+		} else if (rdata.type == dns_rdatatype_nsec) {
+			FAILC(DNS_R_REFUSED,
+			      "explicit NSEC updates are not allowed "
+			      "in secure zones");
+		} else if (rdata.type == dns_rdatatype_rrsig &&
+			   !dns_name_equal(name, zonename)) {
+			FAILC(DNS_R_REFUSED,
+			      "explicit RRSIG updates are currently "
+			      "not supported in secure zones except "
+			      "at the apex");
+		}
+
+		if (ssutable != NULL) {
+			isc_netaddr_t netaddr;
+			dst_key_t *tsigkey = NULL;
+			isc_netaddr_fromsockaddr(&netaddr, &client->peeraddr);
+
+			if (client->message->tsigkey != NULL)
+				tsigkey = client->message->tsigkey->key;
+
+			if (rdata.type != dns_rdatatype_any) {
+				if (!dns_ssutable_checkrules2
+				    (ssutable, client->signer, name, &netaddr,
+				     TCPCLIENT(client),
+				     &ns_g_server->aclenv,
+				     rdata.type, tsigkey))
+				{
+					FAILC(DNS_R_REFUSED,
+					      "rejected by secure update");
+				}
+			} else {
+				if (!ssu_checkall(db, ver, name, ssutable,
+						  client->signer,
+						  &netaddr,
+						  TCPCLIENT(client),
+						  tsigkey))
+				{
+					FAILC(DNS_R_REFUSED,
+					      "rejected by secure update");
+				}
+			}
+		}
+	}
+	if (result != ISC_R_NOMORE)
+		FAIL(result);
+
+	update_log(client, zone, LOGLEVEL_DEBUG,
+		   "update section prescan OK");
+
+	/*
+	 * Process the Update Section.
+	 */
+
+	options = dns_zone_getoptions(zone);
+	options2 = dns_zone_getoptions2(zone);
+	for (result = dns_message_firstname(request, DNS_SECTION_UPDATE);
+	     result == ISC_R_SUCCESS;
+	     result = dns_message_nextname(request, DNS_SECTION_UPDATE))
+	{
+		dns_name_t *name = NULL;
+		dns_rdata_t rdata = DNS_RDATA_INIT;
+		dns_ttl_t ttl;
+		dns_rdataclass_t update_class;
+		bool flag;
+
+		get_current_rr(request, DNS_SECTION_UPDATE, zoneclass,
+			       &name, &rdata, &covers, &ttl, &update_class);
+
+		if (update_class == zoneclass) {
+
+			/*
+			 * RFC1123 doesn't allow MF and MD in master zones.
+			 */
+			if (rdata.type == dns_rdatatype_md ||
+			    rdata.type == dns_rdatatype_mf) {
+				char typebuf[DNS_RDATATYPE_FORMATSIZE];
+
+				dns_rdatatype_format(rdata.type, typebuf,
+						     sizeof(typebuf));
+				update_log(client, zone, LOGLEVEL_PROTOCOL,
+					   "attempt to add %s ignored",
+					   typebuf);
+				continue;
+			}
+			if ((rdata.type == dns_rdatatype_ns ||
+			     rdata.type == dns_rdatatype_dname) &&
+			    dns_name_iswildcard(name)) {
+				char typebuf[DNS_RDATATYPE_FORMATSIZE];
+
+				dns_rdatatype_format(rdata.type, typebuf,
+						     sizeof(typebuf));
+				update_log(client, zone,
+					   LOGLEVEL_PROTOCOL,
+					   "attempt to add wildcard %s record "
+					   "ignored", typebuf);
+				continue;
+			}
+			if (rdata.type == dns_rdatatype_cname) {
+				CHECK(cname_incompatible_rrset_exists(db, ver,
+								      name,
+								      &flag));
+				if (flag) {
+					update_log(client, zone,
+						   LOGLEVEL_PROTOCOL,
+						   "attempt to add CNAME "
+						   "alongside non-CNAME "
+						   "ignored");
+					continue;
+				}
+			} else {
+				CHECK(rrset_exists(db, ver, name,
+						   dns_rdatatype_cname, 0,
+						   &flag));
+				if (flag &&
+				    ! dns_rdatatype_isdnssec(rdata.type))
+				{
+					update_log(client, zone,
+						   LOGLEVEL_PROTOCOL,
+						   "attempt to add non-CNAME "
+						   "alongside CNAME ignored");
+					continue;
+				}
+			}
+			if (rdata.type == dns_rdatatype_soa) {
+				bool ok;
+				CHECK(rrset_exists(db, ver, name,
+						   dns_rdatatype_soa, 0,
+						   &flag));
+				if (! flag) {
+					update_log(client, zone,
+						   LOGLEVEL_PROTOCOL,
+						   "attempt to create 2nd "
+						   "SOA ignored");
+					continue;
+				}
+				CHECK(check_soa_increment(db, ver, &rdata,
+							  &ok));
+				if (! ok) {
+					update_log(client, zone,
+						   LOGLEVEL_PROTOCOL,
+						   "SOA update failed to "
+						   "increment serial, "
+						   "ignoring it");
+					continue;
+				}
+				soa_serial_changed = true;
+			}
+
+			if (rdata.type == privatetype) {
+				update_log(client, zone, LOGLEVEL_PROTOCOL,
+					   "attempt to add a private type "
+					   "(%u) record rejected internal "
+					   "use only", privatetype);
+				continue;
+			}
+
+			if (rdata.type == dns_rdatatype_nsec3param) {
+				/*
+				 * Ignore attempts to add NSEC3PARAM records
+				 * with any flags other than OPTOUT.
+				 */
+				if ((rdata.data[1] &
+				     ~DNS_NSEC3FLAG_OPTOUT) != 0)
+				{
+					update_log(client, zone,
+						   LOGLEVEL_PROTOCOL,
+						   "attempt to add NSEC3PARAM "
+						   "record with non OPTOUT "
+						   "flag");
+					continue;
+				}
+			}
+
+			if ((options & DNS_ZONEOPT_CHECKWILDCARD) != 0 &&
+			    dns_name_internalwildcard(name)) {
+				char namestr[DNS_NAME_FORMATSIZE];
+				dns_name_format(name, namestr,
+						sizeof(namestr));
+				update_log(client, zone, LOGLEVEL_PROTOCOL,
+					   "warning: ownername '%s' contains "
+					   "a non-terminal wildcard", namestr);
+			}
+
+			if ((options2 & DNS_ZONEOPT2_CHECKTTL) != 0) {
+				maxttl = dns_zone_getmaxttl(zone);
+				if (ttl > maxttl) {
+					ttl = maxttl;
+					update_log(client, zone,
+						   LOGLEVEL_PROTOCOL,
+						   "reducing TTL to the "
+						   "configured max-zone-ttl %d",
+						   maxttl);
+				}
+			}
+
+			if (isc_log_wouldlog(ns_g_lctx, LOGLEVEL_PROTOCOL)) {
+				char namestr[DNS_NAME_FORMATSIZE];
+				char typestr[DNS_RDATATYPE_FORMATSIZE];
+				char rdstr[2048];
+				isc_buffer_t buf;
+				int len = 0;
+				const char *truncated = "";
+
+				dns_name_format(name, namestr, sizeof(namestr));
+				dns_rdatatype_format(rdata.type, typestr,
+						     sizeof(typestr));
+				isc_buffer_init(&buf, rdstr, sizeof(rdstr));
+				result = dns_rdata_totext(&rdata, NULL, &buf);
+				if (result == ISC_R_NOSPACE) {
+					len = (int)isc_buffer_usedlength(&buf);
+					truncated = " [TRUNCATED]";
+				} else if (result != ISC_R_SUCCESS) {
+					snprintf(rdstr, sizeof(rdstr), "[dns_"
+						 "rdata_totext failed: %s]",
+						 dns_result_totext(result));
+					len = strlen(rdstr);
+				} else
+					len = (int)isc_buffer_usedlength(&buf);
+				update_log(client, zone, LOGLEVEL_PROTOCOL,
+					   "adding an RR at '%s' %s %.*s%s",
+					   namestr, typestr, len, rdstr,
+					   truncated);
+			}
+
+			/* Prepare the affected RRset for the addition. */
+			{
+				add_rr_prepare_ctx_t ctx;
+				ctx.db = db;
+				ctx.ver = ver;
+				ctx.diff = &diff;
+				ctx.name = name;
+				ctx.oldname = name;
+				ctx.update_rr = &rdata;
+				ctx.update_rr_ttl = ttl;
+				ctx.ignore_add = false;
+				dns_diff_init(mctx, &ctx.del_diff);
+				dns_diff_init(mctx, &ctx.add_diff);
+				CHECK(foreach_rr(db, ver, name, rdata.type,
+						 covers, add_rr_prepare_action,
+						 &ctx));
+
+				if (ctx.ignore_add) {
+					dns_diff_clear(&ctx.del_diff);
+					dns_diff_clear(&ctx.add_diff);
+				} else {
+					result = do_diff(&ctx.del_diff, db, ver,
+							 &diff);
+					if (result == ISC_R_SUCCESS) {
+						result = do_diff(&ctx.add_diff,
+								 db, ver,
+								 &diff);
+					}
+					if (result != ISC_R_SUCCESS) {
+						dns_diff_clear(&ctx.del_diff);
+						dns_diff_clear(&ctx.add_diff);
+						goto failure;
+					}
+					CHECK(update_one_rr(db, ver, &diff,
+							    DNS_DIFFOP_ADD,
+							    name, ttl, &rdata));
+				}
+			}
+		} else if (update_class == dns_rdataclass_any) {
+			if (rdata.type == dns_rdatatype_any) {
+				if (isc_log_wouldlog(ns_g_lctx,
+						     LOGLEVEL_PROTOCOL))
+				{
+					char namestr[DNS_NAME_FORMATSIZE];
+					dns_name_format(name, namestr,
+							sizeof(namestr));
+					update_log(client, zone,
+						   LOGLEVEL_PROTOCOL,
+						   "delete all rrsets from "
+						   "name '%s'", namestr);
+				}
+				if (dns_name_equal(name, zonename)) {
+					CHECK(delete_if(type_not_soa_nor_ns_p,
+							db, ver, name,
+							dns_rdatatype_any, 0,
+							&rdata, &diff));
+				} else {
+					CHECK(delete_if(type_not_dnssec,
+							db, ver, name,
+							dns_rdatatype_any, 0,
+							&rdata, &diff));
+				}
+			} else if (dns_name_equal(name, zonename) &&
+				   (rdata.type == dns_rdatatype_soa ||
+				    rdata.type == dns_rdatatype_ns)) {
+				update_log(client, zone, LOGLEVEL_PROTOCOL,
+					   "attempt to delete all SOA "
+					   "or NS records ignored");
+				continue;
+			} else {
+				if (isc_log_wouldlog(ns_g_lctx,
+						     LOGLEVEL_PROTOCOL))
+				{
+					char namestr[DNS_NAME_FORMATSIZE];
+					char typestr[DNS_RDATATYPE_FORMATSIZE];
+					dns_name_format(name, namestr,
+							sizeof(namestr));
+					dns_rdatatype_format(rdata.type,
+							     typestr,
+							     sizeof(typestr));
+					update_log(client, zone,
+						   LOGLEVEL_PROTOCOL,
+						   "deleting rrset at '%s' %s",
+						   namestr, typestr);
+				}
+				CHECK(delete_if(true_p, db, ver, name,
+						rdata.type, covers, &rdata,
+						&diff));
+			}
+		} else if (update_class == dns_rdataclass_none) {
+			char namestr[DNS_NAME_FORMATSIZE];
+			char typestr[DNS_RDATATYPE_FORMATSIZE];
+
+			/*
+			 * The (name == zonename) condition appears in
+			 * RFC2136 3.4.2.4 but is missing from the pseudocode.
+			 */
+			if (dns_name_equal(name, zonename)) {
+				if (rdata.type == dns_rdatatype_soa) {
+					update_log(client, zone,
+						   LOGLEVEL_PROTOCOL,
+						   "attempt to delete SOA "
+						   "ignored");
+					continue;
+				}
+				if (rdata.type == dns_rdatatype_ns) {
+					int count;
+					CHECK(rr_count(db, ver, name,
+						       dns_rdatatype_ns,
+						       0, &count));
+					if (count == 1) {
+						update_log(client, zone,
+							   LOGLEVEL_PROTOCOL,
+							   "attempt to "
+							   "delete last "
+							   "NS ignored");
+						continue;
+					}
+				}
+			}
+			dns_name_format(name, namestr, sizeof(namestr));
+			dns_rdatatype_format(rdata.type, typestr,
+					     sizeof(typestr));
+			update_log(client, zone, LOGLEVEL_PROTOCOL,
+				   "deleting an RR at %s %s", namestr, typestr);
+			CHECK(delete_if(rr_equal_p, db, ver, name, rdata.type,
+					covers, &rdata, &diff));
+		}
+	}
+	if (result != ISC_R_NOMORE)
+		FAIL(result);
+
+	/*
+	 * Check that any changes to DNSKEY/NSEC3PARAM records make sense.
+	 * If they don't then back out all changes to DNSKEY/NSEC3PARAM
+	 * records.
+	 */
+	if (! ISC_LIST_EMPTY(diff.tuples))
+		CHECK(check_dnssec(client, zone, db, ver, &diff));
+
+	if (! ISC_LIST_EMPTY(diff.tuples)) {
+		unsigned int errors = 0;
+		CHECK(dns_zone_nscheck(zone, db, ver, &errors));
+		if (errors != 0) {
+			update_log(client, zone, LOGLEVEL_PROTOCOL,
+				   "update rejected: post update name server "
+				   "sanity check failed");
+			result = DNS_R_REFUSED;
+			goto failure;
+		}
+	}
+	if (! ISC_LIST_EMPTY(diff.tuples)) {
+		result = dns_zone_cdscheck(zone, db, ver);
+		if (result == DNS_R_BADCDS || result == DNS_R_BADCDNSKEY) {
+			update_log(client, zone, LOGLEVEL_PROTOCOL,
+				   "update rejected: bad %s RRset",
+				   result == DNS_R_BADCDS ? "CDS" : "CDNSKEY");
+			result = DNS_R_REFUSED;
+			goto failure;
+		}
+		if (result != ISC_R_SUCCESS)
+			goto failure;
+
+	}
+
+	/*
+	 * If any changes were made, increment the SOA serial number,
+	 * update RRSIGs and NSECs (if zone is secure), and write the update
+	 * to the journal.
+	 */
+	if (! ISC_LIST_EMPTY(diff.tuples)) {
+		char *journalfile;
+		dns_journal_t *journal;
+		bool has_dnskey;
+
+		/*
+		 * Increment the SOA serial, but only if it was not
+		 * changed as a result of an update operation.
+		 */
+		if (! soa_serial_changed) {
+			CHECK(update_soa_serial(db, ver, &diff, mctx,
+				       dns_zone_getserialupdatemethod(zone)));
+		}
+
+		CHECK(check_mx(client, zone, db, ver, &diff));
+
+		CHECK(remove_orphaned_ds(db, ver, &diff));
+
+		CHECK(rrset_exists(db, ver, zonename, dns_rdatatype_dnskey,
+				   0, &has_dnskey));
+
+#define ALLOW_SECURE_TO_INSECURE(zone) \
+	((dns_zone_getoptions(zone) & DNS_ZONEOPT_SECURETOINSECURE) != 0)
+
+		CHECK(rrset_exists(db, oldver, zonename, dns_rdatatype_dnskey,
+				   0, &had_dnskey));
+		if (!ALLOW_SECURE_TO_INSECURE(zone)) {
+			if (had_dnskey && !has_dnskey) {
+				update_log(client, zone, LOGLEVEL_PROTOCOL,
+					   "update rejected: all DNSKEY "
+					   "records removed and "
+					   "'dnssec-secure-to-insecure' "
+					   "not set");
+				result = DNS_R_REFUSED;
+				goto failure;
+			}
+		}
+
+		CHECK(rollback_private(db, privatetype, ver, &diff));
+
+		CHECK(add_signing_records(db, privatetype, ver, &diff));
+
+		CHECK(add_nsec3param_records(client, zone, db, ver, &diff));
+
+		if (had_dnskey && !has_dnskey) {
+			/*
+			 * We are transitioning from secure to insecure.
+			 * Cause all NSEC3 chains to be deleted.  When the
+			 * the last signature for the DNSKEY records are
+			 * remove any NSEC chain present will also be removed.
+			 */
+			 CHECK(dns_nsec3param_deletechains(db, ver, zone,
+							   true, &diff));
+		} else if (has_dnskey && isdnssec(db, ver, privatetype)) {
+			uint32_t interval;
+			dns_update_log_t log;
+
+			interval = dns_zone_getsigvalidityinterval(zone);
+			log.func = update_log_cb;
+			log.arg = client;
+			result = dns_update_signatures(&log, zone, db, oldver,
+						       ver, &diff, interval);
+
+			if (result != ISC_R_SUCCESS) {
+				update_log(client, zone,
+					   ISC_LOG_ERROR,
+					   "RRSIG/NSEC/NSEC3 update failed: %s",
+					   isc_result_totext(result));
+				goto failure;
+			}
+		}
+
+		maxrecords = dns_zone_getmaxrecords(zone);
+		if (maxrecords != 0U) {
+			result = dns_db_getsize(db, ver, &records, NULL);
+			if (result == ISC_R_SUCCESS && records > maxrecords) {
+				update_log(client, zone, ISC_LOG_ERROR,
+					   "records in zone (%"
+					   PRIu64
+					   ") exceeds max-records (%u)",
+					   records, maxrecords);
+				result = DNS_R_TOOMANYRECORDS;
+				goto failure;
+			}
+		}
+
+		journalfile = dns_zone_getjournal(zone);
+		if (journalfile != NULL) {
+			update_log(client, zone, LOGLEVEL_DEBUG,
+				   "writing journal %s", journalfile);
+
+			journal = NULL;
+			result = dns_journal_open(mctx, journalfile,
+						  DNS_JOURNAL_CREATE, &journal);
+			if (result != ISC_R_SUCCESS)
+				FAILS(result, "journal open failed");
+
+			result = dns_journal_write_transaction(journal, &diff);
+			if (result != ISC_R_SUCCESS) {
+				dns_journal_destroy(&journal);
+				FAILS(result, "journal write failed");
+			}
+
+			dns_journal_destroy(&journal);
+		}
+
+		/*
+		 * XXXRTH  Just a note that this committing code will have
+		 *	   to change to handle databases that need two-phase
+		 *	   commit, but this isn't a priority.
+		 */
+		update_log(client, zone, LOGLEVEL_DEBUG,
+			   "committing update transaction");
+
+		dns_db_closeversion(db, &ver, true);
+
+		/*
+		 * Mark the zone as dirty so that it will be written to disk.
+		 */
+		dns_zone_markdirty(zone);
+
+		/*
+		 * Notify slaves of the change we just made.
+		 */
+		dns_zone_notify(zone);
+
+		/*
+		 * Cause the zone to be signed with the key that we
+		 * have just added or have the corresponding signatures
+		 * deleted.
+		 *
+		 * Note: we are already committed to this course of action.
+		 */
+		for (tuple = ISC_LIST_HEAD(diff.tuples);
+		     tuple != NULL;
+		     tuple = ISC_LIST_NEXT(tuple, link)) {
+			isc_region_t r;
+			dns_secalg_t algorithm;
+			uint16_t keyid;
+
+			if (tuple->rdata.type != dns_rdatatype_dnskey)
+				continue;
+
+			dns_rdata_tostruct(&tuple->rdata, &dnskey, NULL);
+			if ((dnskey.flags &
+			     (DNS_KEYFLAG_OWNERMASK|DNS_KEYTYPE_NOAUTH))
+				 != DNS_KEYOWNER_ZONE)
+				continue;
+
+			dns_rdata_toregion(&tuple->rdata, &r);
+			algorithm = dnskey.algorithm;
+			keyid = dst_region_computeid(&r, algorithm);
+
+			result = dns_zone_signwithkey(zone, algorithm, keyid,
+						      (tuple->op == DNS_DIFFOP_DEL));
+			if (result != ISC_R_SUCCESS) {
+				update_log(client, zone, ISC_LOG_ERROR,
+					   "dns_zone_signwithkey failed: %s",
+					   dns_result_totext(result));
+			}
+		}
+
+		/*
+		 * Cause the zone to add/delete NSEC3 chains for the
+		 * deferred NSEC3PARAM changes.
+		 *
+		 * Note: we are already committed to this course of action.
+		 */
+		for (tuple = ISC_LIST_HEAD(diff.tuples);
+		     tuple != NULL;
+		     tuple = ISC_LIST_NEXT(tuple, link)) {
+			unsigned char buf[DNS_NSEC3PARAM_BUFFERSIZE];
+			dns_rdata_t rdata = DNS_RDATA_INIT;
+			dns_rdata_nsec3param_t nsec3param;
+
+			if (tuple->rdata.type != privatetype ||
+			    tuple->op != DNS_DIFFOP_ADD)
+				continue;
+
+			if (!dns_nsec3param_fromprivate(&tuple->rdata, &rdata,
+						   buf, sizeof(buf)))
+				continue;
+			dns_rdata_tostruct(&rdata, &nsec3param, NULL);
+			if (nsec3param.flags == 0)
+				continue;
+
+			result = dns_zone_addnsec3chain(zone, &nsec3param);
+			if (result != ISC_R_SUCCESS) {
+				update_log(client, zone, ISC_LOG_ERROR,
+					   "dns_zone_addnsec3chain failed: %s",
+					   dns_result_totext(result));
+			}
+		}
+	} else {
+		update_log(client, zone, LOGLEVEL_DEBUG, "redundant request");
+		dns_db_closeversion(db, &ver, true);
+	}
+	result = ISC_R_SUCCESS;
+	goto common;
+
+ failure:
+	/*
+	 * The reason for failure should have been logged at this point.
+	 */
+	if (ver != NULL) {
+		update_log(client, zone, LOGLEVEL_DEBUG,
+			   "rolling back");
+		dns_db_closeversion(db, &ver, false);
+	}
+
+ common:
+	dns_diff_clear(&temp);
+	dns_diff_clear(&diff);
+
+	if (oldver != NULL)
+		dns_db_closeversion(db, &oldver, false);
+
+	if (db != NULL)
+		dns_db_detach(&db);
+
+	if (ssutable != NULL)
+		dns_ssutable_detach(&ssutable);
+
+	isc_task_detach(&task);
+	uev->result = result;
+	if (zone != NULL)
+		INSIST(uev->zone == zone); /* we use this later */
+	uev->ev_type = DNS_EVENT_UPDATEDONE;
+	uev->ev_action = updatedone_action;
+	isc_task_send(client->task, &event);
+
+	INSIST(ver == NULL);
+	INSIST(event == NULL);
+}
+
+static void
+updatedone_action(isc_task_t *task, isc_event_t *event) {
+	update_event_t *uev = (update_event_t *) event;
+	ns_client_t *client = (ns_client_t *) event->ev_arg;
+
+	UNUSED(task);
+
+	INSIST(event->ev_type == DNS_EVENT_UPDATEDONE);
+	INSIST(task == client->task);
+
+	INSIST(client->nupdates > 0);
+	switch (uev->result) {
+	case ISC_R_SUCCESS:
+		inc_stats(uev->zone, dns_nsstatscounter_updatedone);
+		break;
+	case DNS_R_REFUSED:
+		inc_stats(uev->zone, dns_nsstatscounter_updaterej);
+		break;
+	default:
+		inc_stats(uev->zone, dns_nsstatscounter_updatefail);
+		break;
+	}
+	if (uev->zone != NULL)
+		dns_zone_detach(&uev->zone);
+	client->nupdates--;
+	respond(client, uev->result);
+	isc_event_free(&event);
+	ns_client_detach(&client);
+}
+
+/*%
+ * Update forwarding support.
+ */
+
+static void
+forward_fail(isc_task_t *task, isc_event_t *event) {
+	ns_client_t *client = (ns_client_t *)event->ev_arg;
+
+	UNUSED(task);
+
+	INSIST(client->nupdates > 0);
+	client->nupdates--;
+	respond(client, DNS_R_SERVFAIL);
+	isc_event_free(&event);
+	ns_client_detach(&client);
+}
+
+
+static void
+forward_callback(void *arg, isc_result_t result, dns_message_t *answer) {
+	update_event_t *uev = arg;
+	ns_client_t *client = uev->ev_arg;
+	dns_zone_t *zone = uev->zone;
+
+	if (result != ISC_R_SUCCESS) {
+		INSIST(answer == NULL);
+		uev->ev_type = DNS_EVENT_UPDATEDONE;
+		uev->ev_action = forward_fail;
+		inc_stats(zone, dns_nsstatscounter_updatefwdfail);
+	} else {
+		uev->ev_type = DNS_EVENT_UPDATEDONE;
+		uev->ev_action = forward_done;
+		uev->answer = answer;
+		inc_stats(zone, dns_nsstatscounter_updaterespfwd);
+	}
+	isc_task_send(client->task, ISC_EVENT_PTR(&uev));
+	dns_zone_detach(&zone);
+}
+
+static void
+forward_done(isc_task_t *task, isc_event_t *event) {
+	update_event_t *uev = (update_event_t *) event;
+	ns_client_t *client = (ns_client_t *)event->ev_arg;
+
+	UNUSED(task);
+
+	INSIST(client->nupdates > 0);
+	client->nupdates--;
+	ns_client_sendraw(client, uev->answer);
+	dns_message_destroy(&uev->answer);
+	isc_event_free(&event);
+	ns_client_detach(&client);
+}
+
+static void
+forward_action(isc_task_t *task, isc_event_t *event) {
+	update_event_t *uev = (update_event_t *) event;
+	dns_zone_t *zone = uev->zone;
+	ns_client_t *client = (ns_client_t *)event->ev_arg;
+	isc_result_t result;
+
+	result = dns_zone_forwardupdate(zone, client->message,
+					forward_callback, event);
+	if (result != ISC_R_SUCCESS) {
+		uev->ev_type = DNS_EVENT_UPDATEDONE;
+		uev->ev_action = forward_fail;
+		isc_task_send(client->task, &event);
+		inc_stats(zone, dns_nsstatscounter_updatefwdfail);
+		dns_zone_detach(&zone);
+	} else
+		inc_stats(zone, dns_nsstatscounter_updatereqfwd);
+	isc_task_detach(&task);
+}
+
+static isc_result_t
+send_forward_event(ns_client_t *client, dns_zone_t *zone) {
+	char namebuf[DNS_NAME_FORMATSIZE];
+	char classbuf[DNS_RDATACLASS_FORMATSIZE];
+	isc_result_t result = ISC_R_SUCCESS;
+	update_event_t *event = NULL;
+	isc_task_t *zonetask = NULL;
+	ns_client_t *evclient;
+
+	/*
+	 * This may take some time so replace this client.
+	 */
+	if (!client->mortal && (client->attributes & NS_CLIENTATTR_TCP) == 0)
+		CHECK(ns_client_replace(client));
+
+	event = (update_event_t *)
+		isc_event_allocate(client->mctx, client, DNS_EVENT_UPDATE,
+				   forward_action, NULL, sizeof(*event));
+	if (event == NULL)
+		FAIL(ISC_R_NOMEMORY);
+	event->zone = zone;
+	event->result = ISC_R_SUCCESS;
+
+	evclient = NULL;
+	ns_client_attach(client, &evclient);
+	INSIST(client->nupdates == 0);
+	client->nupdates++;
+	event->ev_arg = evclient;
+
+	dns_name_format(dns_zone_getorigin(zone), namebuf,
+			sizeof(namebuf));
+	dns_rdataclass_format(dns_zone_getclass(zone), classbuf,
+			      sizeof(classbuf));
+
+	ns_client_log(client, NS_LOGCATEGORY_UPDATE, NS_LOGMODULE_UPDATE,
+		      LOGLEVEL_PROTOCOL, "forwarding update for zone '%s/%s'",
+		      namebuf, classbuf);
+
+	dns_zone_gettask(zone, &zonetask);
+	isc_task_send(zonetask, ISC_EVENT_PTR(&event));
+
+ failure:
+	if (event != NULL)
+		isc_event_free(ISC_EVENT_PTR(&event));
+	return (result);
+}